There are a variety of factors that lead to and impact rudder load. These include:

• Boat speed (force increases with the square of the increase in speed)
• Rudder angle of attack (AOA) in which load is proportional to angle
• Rudder stall angle beyond which the rudder no longer develops significant lift
• Weight of the vessel and hull immersion
• Pivot point of the vessel
• Wave impact on the stern
• Grounding loads

With our type of hull shape and displacement, there is little resistance to turning, and the boats tend to pivot on the bow. When significant load is applied to the stern, say by the rudder developing turning force, the stern slips sideways, pivoting as it were on the bow. In all cases, save for one, this minimizes the force the rudder can actually generate in the rudder shaft.

That exception is when a breaking crest slaps the stern from near abeam, and the rudder attempts to correct course while fighting the wave at the same time. This would be our idea of a high load scenario.

As you will see in a moment, the various rules handle angle of attack differently. In the real world the AOA is self-limiting. Past a certain AOA the rudder flow breaks down, and lift is mostly lost. This often happens at a lower AOA than the various rules contemplate

Speed, in our case, is an interesting calculation. Do we use normal cruise, maximum smooth water speed, or surfing? In the latter case do you take credit for the circular molecule motion (theoretical) which is said to reduce rudder efficiency when surfing?

As you will see below, our rudder shafts are very conservatively engineered for the seagoing loads, and have huge factors of safety. What we are more concerned with is engineering for mistakes in navigation, i.e. hitting the bricks. The key here is trying to engineer the bottom portion of the rudder so that it is weaker than the shaft, and bends or breaks off before the rudder shaft reaches its elastic limit (deforms). This not easily engineered, and at best all you can do is hope you have it right. But as we have yet to bend a rudder shaft, we think we may be headed in the right direction.

The name of this game is damage tolerance, having a degree of probability of running aground and then getting off and continuing to cruise without visiting a boat yard. Odds are one of the stabilizer fins might have departed, but we can live with that. The steering system must remain functional. This brings us to the type of rudder support, and if the bottom edge is exposed or there is a protective beam between skeg and rudder bottom.

Protective beams are quite common. However, if you are bouncing the weight of the aft end of the boat in the middle of that beam, odds are it will bend upwards. Then it jams the rudder or prop, or both. Pick your poison. A skeg hung rudder requires a bottom rudder bearing. If the skeg is damaged, and the bottom bearing jammed or chewed off, there is no longer sufficient support for steering the boat. All of which adds up to one of the reasons we use spade rudders. Properly engineered, they provide the highest factors of safety in the event of a grounding. And by far the best steering control.

Now some numbers. The table below has data for the Lloyds Special Service Calculations and American Bureau of Shipping Racing Yachts and Motor Yachts. These include input data for the size and shape of the rudder, and the speed, along with angle of attack. The column headed “Lower Stock Rule” has the required diameter of a solid aluminum rudder stock. The far right column, “Twice Rule Nominal” is the required solid aluminum stock diameter for two times the required rule stiffness. Dimensions are given in millimeters (divide by 25.4 to convert to inches).

There are three sets of speeds shown: 12 knots, which we consider to be the normal maximum cruising speed, 14 knots, which will be often seen surfing, and 20 knots, representing the peak surfing speed we are likely to see on occasion (although more is possible). Starting at the top, at fourteen knots, twice the rule induced stiffness comes out to 120mm (just under five inches) of rudder stock which also happens to represent the Lloyds SSC diameter at 20 knots on the basis of 100% of the rule requirement.

ABS for racing yachts has no speed input, but does allow changing the angle of attack for the rudder. Here we see 110mm (4.4″) solid stock working out at 35 degrees of deflection. ABS for motor yachts allows us to vary speed, but imputes a 35 degree AOA. Here 20 knots and a 35 degree AOA on the rudder equates to 5″/125mm solid shaft. Same AOA and fourteen knots, gives us twice the ABS rule stiffness .

All of the above confirms what we knew starting out, namely that a 125mm/5″ solid shaft would do the trick. We just wanted to run a few numbers to verify all of this.

Comparing this now to our sailboat rudders, this is a heavier stock for a smaller rudder than would be the case for a sailing yacht. On the other hand, if we mess up and put the boat onto a reef, the loads are potentially higher because of the much heavier displacement. Of course the FPBs have skegs to help protect the rudder and props when aground where the sailboats had nothing. All in all, our instinct says this is a very conservative structural system

At a later date we will discuss making the tip of the rudder blades frangible, so they fail before the ruder stock permanently deflects.

Here is a sight guaranteed to please… FPB 64-10 has begun its journey (right) while FPB 97-1 has its mast structure well under way.

Ten years ago when we began work on the FPB 83 Wind Horse, the matriarch of the FPB family, nobody, least of all ourselves, would have predicted this outcome. Even more exciting to us is the fact that there are now eight FPBs actively cruising.

Masts up! Basic mast structure on the FPB 97 can be seen here. Note the access panels, gooseneck fittings for the booms, and in line extension for the topping lifts.

Matrix deck roof framework.

And for a sense of scale, a look through what will become the door into the FPB 97 gray room.

This is the inside of the coaming on the FPB 97, aft of the great room aft bulkhead. The vent pipes are for the fresh air system into the port side of the systems room below.

Now a pair of FPB 64 photos: FPB 64-8 above, and FPB 64-9 below.

These boats are separated by three months in terms of schedule.

We’ll close with this look at some of the wiring on FPB 64-8.

We feel that the most dangerous operation on any motor yacht is dinghy launch and retrieval. This applies to our FPB as well, even though our approach, with the dink on the main deck, is much easier (and we think safer) to handle than most. The heavier the dink, the bigger the risk, and this new dink is considerably weightier than our old, trending towards 1200 pounds/550kg. So we have been fiddling away at a better handling system since the beginning of the design cycle. What follows has been adapted from the approach being considered for FPB 97-1, and represents what we think is a step forward from where we have been in the past.

Before getting into the details, a few parameters:

• We want to reduce the handling risks posed when the mothership is rolled by a wake or a swell sweeping into an anchorage
• In the event of an abandon ship scenario, most probably due to fire in our thinking, we want to be able to launch the dink as expeditiously as possible, probably without the use of power
• The day-to-day process of lowering and raising the dinghy should be easy enough that there is no hesitation retrieving the dink once we’ve finished using it
• It would be nice if we could single-hand this operation in calm anchorages

We will start with the dink alongside, ready to hoist. The dinghy halyard will be attached to the horizontal pipe on the t-top, via a strap. With the t-top at just above the belting we can lean over the railing to attach the halyard or squeeze between the rails if required.

The dink is then hoisted to where it is still below the mothership belting (toe rail).

The boom after guy is adjusted so that the boom is locked in the correct position and cannot swing outboard. There will be a sewn mark on the guy to precisely indicate the correct position. With the dinghy hull kept in place and the guy correctly adjusted, the dinghy cannot rotate more than a tiny amount.

Here is where things get interesting. We then connect a two-to-one tackle arrangement to the dinghy, with a snap shackle on a single block. This gives us a 2-1 purchase with which we can control the dinghy swing, and pull it inboard with a bit of leverage.

The control line, an FPB equivalent of the Barber Haulers we used to adjust our jib leads half a century ago (named after the Barber brothers of Flying Dutchman fame), is dead-ended on the aft scuttle, then runs through a snatch block/snapshackle affair on the dinghy rail, after which back to the scuttle and through a Lewmar rope clutch. The block shown bottom right will help us use this barber hauler from other areas on the aft deck.

Now we pull a couple of pins and fold down the staple rail.

If the boat rolls to port, and the dink swings in, it will be stopped by the stanchion shown center right in the previous rendering, and by coming up hard against the scuttle. Tailing the control line through the rope clutch as the boat rolls to port takes up slack and prevents the dink from rolling away to starboard when the mother ship rolls back. Once the dink is on the chocks, and the control line snugly tightened, the dinghy cannot move. We can then take our time getting the seagoing lashings set and securing the boom guys.

The chocks are a big part of this design concept, as are the folding safety rails. Both are what enable us to launch the dink with minimal lifting off the deck.

Now a word on control of the booms, and winch operation. There are four lines per boom with which we have to deal on the new FPB 78. These are now brought to a bank of clutches on the aft side of the masts. These are the fore guy, after guy, dinghy halyard, and end of boom halyard for flopper stoppers.

We want somewhere to neatly store the four lines per side. That is where this mast locker door, which leads to a rope tails storage locker, comes into play (the tails slip through the slot in the door).

The launching sequence is much simpler than the past, as the off center dinghy weight heels the boat as the boom is eased out. The sequence with the new system is as follows:

• Remove tie downs
• Connect control line to dinghy gunnel
• Attach halyard if not already attached (it usually is connected)
• Ease after guy and gunnel control line to their pre-marked positions
• Hoist a fraction of an inch to raise off the chocks
• Push dink outboard
• Lower so the bottom is below the mothership belting
• Raise staple rail
• Disconnect gunnel control
• Finish lowering

We are guessing the entire process, up or down, will probably take two to three minutes in calm conditions.

There are four keys to this concept:

• The chock design which minimizes lifting
• The folding staple rail section that eliminates the need to raise the dinghy three feet/90cm off the deck
• The gunnel control tackle
• The workshop door scuttle that acts as a stop and a position for the dink

Now, we just have to wait a while to see how this works.

Of all the features on our new FPB Dream Machine that excite us, the one at the top of Steve’s list is the workshop. It allows an array of tools and storage that will delight anyone who works on the boat. And it will be a major factor in increasing maintenance and repair options anywhere we cruise.

The proximity to the engine room, with the option of direct access that can be closed off, will make chores underway a lot more pleasant, as we will be able to isolate engine room heat and noise while messing about in the workshop. At anchor the swim step door can left open to keep us cool.

We are not yet certain of the bench tools we will install except for a drill press, disc sander, and a press, perhaps the most desirable of all. Any time we have a bearing to replace, or maybe a gear on a pump shaft, a press is necessary. Without it we have to find a machine shop. With it if we are not confident in our own abilities there will be someone aboard a yacht, fishing boat, or in the village ashore, who can use this to help us rebuild the whatever.

A proper workshop means having tools and spare parts close at hand.

As mentioned in other posts, there is plentiful storage here, both above and below the sole. The twelve bins shown to the left represent the volume we used on Wind Horse to stow all of her spare parts in the basement.

The small plastic containers that lined the engine room shelves before will now neatly find a home on the hullside and bulkhead. And how about two separate stacks of tool drawers. This is sufficient tool storage space to get almost all our tools into the drawers.

There will be room left over for dock lines, dive gear, a dive compressor if we go that route, and various items normally associated with water sports and dinghies, all previously stowed in the forepeak. Having this aft where it is used,  not having to drag it all back and forth between bow and stern, is another bonus of this approach.

The black water (sewage) tanks and all other systems except autopilot steering, are in the engine room proper. This leaves most of the area under the swim step, and below the sole, available for even more storage.  In the rendering above we are looking aft, under the swim step. Except for exhaust plumbing, isolation transformer, and misc. plumbing exhausts, this large area is available for the storage of oils, and other items which engine rooms find dear, such as oil absorbing pads, coolant, and hydraulic oil.

At anchor, if the doors to the swim step and engine room (there is one on each engine room bulkhead) are left open, there will be a lovely breeze coming through the aft end of the boat. And the two aft doors are sufficiently wide to allow removal of an almost intact genset or engine.

The final layout of this area will take considerable time to get right, as in several years after launching, and whatever we do will change with time, so we will endeavor to keep the implementation as flexible and easily modified  as possible.

Now all this talk of water and related toys has us excited, so we will close with a rendering at anchor in shallow water–let’s say the Bahamas.

I had the distinct pleasure of spending some time with Valerie and Stan Creighton as they became acquainted with their new baby back in March. Fast forward to June and they’ve just completed an adventurous passage from New Zealand to Fiji.

Buffalo Nickel and crew are safely ensconced in Lautoka harbor after a successful journey. But we think you’ll enjoy their own narrative summary of the passage. With Stan and Val’s permission, we’ve posted their missive from 5 days out of NZ below. Read on, and then be sure to check out their great blog at buffalonickelblog.com.

PS: Watch for a weather and tactics analysis on the Buffalo Nickel passage, that of Iron Lady to Papeete, and the New Caledonia to New Zealand trip a few weeks ago with Grey Wolf. They all feature dealing with an unusually boisterous equinoctal gale season. We think you will find it interesting.

Now, on with the Buffs.

Passage New Zealand to Fiji, Day 5

This should have been the day we made our landfall in Lautoka. But with all the scurrying hither and yon avoiding nasty weather, we lost a day. The great news is conditions have been lovely last night and especially today.

Lat: 20 26 S
Long: 176 03 E
Winds: light and variable, NW, expected to continue clocking around us to end up SE.
Seas: nearly flat

To summarize our weather conundrum: we departed Marsden Cove, NZ on Thursday, knowing there was a low pressure system developing south of Fiji. This system was expected to be relatively weak, migrate SE and not be a factor for us by the time we arrived in the neighborhood. After we left, we downloaded a weather file update known as a GRIB file. It showed the low developing much stronger than anticipated, and also further west. This could be a serious problem for us if we ended up to the east of it as it made its way southeast. It could mean truly awful winds and seas hitting us head-on, which is no fun in a best-case and truly dangerous in a worst-case scenario. We initially about-faced to head back toward Opua, NZ, but then thought better of it.

We diverted northwest instead, to stay on the ‘correct’ side of the low. This put the wind and seas more behind us, so although we had winds in the high 30′s and big seas they were manageable. We were able to do this because we have a boat that moves fast enough to employ such tactics when needed. Several slower sailboats got caught out southeast of this low, and had the same 18 foot seas and 40 knots of wind right on their noses. They sounded truly exhausted when we heard them on the SSB radio net at the end of the day.

But before long we had to head northeast, or risk getting caught ahead of a different low coming from the Tasman Sea south of us. In between these two unsettled pieces of ocean was a safe zone which we succeeded in following, arcing around to the west instead of taking our bee-line. This left us exposed to less comfortable seas for a day or so… we set our heading to take the seas off our bow, but there were plenty of big waves hitting us on our starboard beam thrown into the mix. The four of us were astounded at how gracefully Buffalo Nickel handled these various conditions. And being newly acquainted with her, we haven’t even begun to start pushing buttons and varying settings on our stabilizers, which, who knows, could have made our ride even more tolerable in those hours.

We cruised Costa Rica and Panama in our fiberglass Selene trawler, cruising grounds known for having dangerous logs, huge trees and other debris floating around, and managed never to hit more than a twig though we saw plenty out there. Now here we are on a passage through a big ‘clean’ ocean, no debris in sight. And we’ve been hit by two logs. The second one was more like a sequoia. Nearly submerged, covered with barnacles. Hit our starboard side just ahead of the house with a loud bang, then whipped around and smacked us amidships so hard it sounded like a grenade explosion, sending a huge volume of water up past the tops of our house windows.

All four of us have white hair now as a result, which is a bummer as I’d just had my roots done. But the Stans checked the stabilizer fin on that side for presence (!) and function, it seems fine, and no vibration at all in the propeller. With a hull construction like ours, it’s not the hull that one needs to worry about so much as all the stuff sticking out of it. But so far as we can tell, no harm done.

So we are happy sailors. Skies are nearly clear, temp outside is a comfy 77 and water temp has risen to 82. Stan fished yesterday and caught a skipjack, not the ahi I ordered. He had fun all the same, and tonight it’s chicken stir-fry with peanut sauce over sushi rice, after we digest Anchovy Stan’s delicious guacamole.

Thanks loads to Stan’s daughter Kristy for posting these blog entries on our behalf. With any luck, we’ll get some internet going right after we make landfall and get some pics up real soon.

Cheers!

If you are still with us after all the preceding posts, we’d like to congratulate you on your studiousness! We started out to do something short and sweet, but the best of intentions have gone astray with the excitement of sharing. On the assumption that if you are still with us you might want a few hard numbers, we offer a last bit of information.

The Numbers:
 

Comparing The Different FPBs:

How does the  FPB 78 compare to Wind Horse, the FPB 64, and the 97? The answer is that there is no way to directly compare the designs as they are each optimized towards different goals. But there are definite physical differences which are quantifiable.

We have used the table above as part of our own analysis. Although the FPB 78 is not that much longer, just 22% on deck if you go by the FPB 64 original design, the new boat has considerably more freeboard.

The added height as well as length and beam (the latter in scale – no fat boats here!) creates a substantial increase in volume. Waterline beam remains svelte. Careful attention to weight up high, together with increased tankage, maintain a favorable stability curve and the seagoing characteristics of the FPB series, including steering control, capsize resistance, knockdown recovery, and comfortable motion at sea.

Here is a scaled comparison of the great rooms on the FPB 78 and the 64.

Next, the Matrix deck of the 78 and the flying bridge of the 64.

The forward suite is, as we said at the beginning, passable (OK, more than passable…totally awesome).

And the guest quarters overly generous (anyone who knows us will recognize which family member has influenced this allotment).

Comparing the new boat to Wind Horse is more difficult for us. There is a substantial emotional attachment left over from our long term relationship. Having safely transported us 60,000 nautical miles to cruising grounds we’d only dreamed of before, in a manner so comfortable that we still wonder at it all, there will always be a soft spot in our hearts for her. On the other hand, this new FPB allows us to continue the cruising life we love, with crew, when this becomes desirable.

There are of course refinements in propulsion, ventilation, general systems, and hull shape – that comes with the experience gained from our growing fleet of FPBs. The FPB 78 will be quieter under way, with even greater range than either Wind Horse or the FPB 64. And the FPB 78 will be more comfortable heading into the seas. One of the features we look forward to the most is the ability to dry out in tidal estuaries. This will open up a whole new world for us to explore. Now we just have to be patient while the Kiwis work their magic.

As you maybe able to discern, we are excited about what this new design offers us, most important of which is the ability to continue doing what we love, exploring the world around us from the comfort of our own floating home, and chasing the dream.

We’ll see you out there - Linda and Steve

Deck Gear, Docking, Anchoring, and Dinghy Handling Gear:

We have adopted much of the deck gear concept that has been developed for the FPB 97, and added a few refinements to the package.

One of these is a wider anchoring sprit. We often find ourselves threading snubber or spring lines through the fairlead at the end of the sprit. The wider base will make this much easier. The lifelines have been run out and end on the fairlead. There may be a tradeoff when heading upwind in steep seas with the sprit this much wider, or maybe not. One of those lessons that awaits.

There are now powered winches forward and aft to use for kedging, warping, and mooring stern-to (Med Style): four total.

On the aft side of the starboard mast is a power winch, sized for dinghy launching and handling dock lines.. The port dinghy winch is on deck, so it does not interfere with our use of the deck level docking controls.  The life raft lives under the seat, to port of the great room exhaust fans.

Here is a look at an alternate layout we briefly considered, where the area under the stairs was totally enclosed. This would provide lots of additional storage space, and even room for a deck level day head. The tradeoff is loss of the seating under the stairs, and a bit of window space and the resulting view from inside. We will come back to this aspect of the boat at a later date.

The two boom guys and halyards will run through rope clutches just above the winch. We are working through the details of rope storage, tentatively scheduled for the lockers inside of the masts. There is a full height locker adjacent to the entry door, where we will keep jackets, foul weather gear, shots, and abandon ship bags. The boom control clutches, winch, and engine room air intake are all shown here in some detail.

There is room on the aft deck for a large power dink and a second lighter dinghy for exercise and/or going to the beach when the big dinghy is too heavy to drag out of the surf. We have the space on the port side to fit one of the AB aluminum bottom RIBs of about 10.5′ (3.5m), or a 14-foot rowing skiff.

We will be able to launch and retrieve the big power dinghy single-handed in calm anchorages.

The swim ladder is integrated into the swim step in a manner similar to what has been developed for the FPB 97.

At the same time we have been fiddling with the concept details for the FPB 78, we have been at work on what we think will be the ultimate dinghy, designed from the start for the aft deck.

This is a riff on the dinghy Circa have been supplying to most of the FPB 64 owners. For cold climates there is a protected helm, with room for two. And a built-in tentlike cover to keep the groceries dry when it is wet.

If you need serious protection, zip up the cover.

The T-top is permanent, providing shade in the tropics. Note the towing post, good for skiers or other vessels.

We will have a solar panel mounted on the roof. The pipe is where the lifting strap will attach for hoisting.

If this seems like a lot of dialogue about a dinghy, it is because we think the capabilities of this little vessel will substantially enhance our cruising capabilities. Fitting this much dinghy onto the aft deck, leaving sufficient room for a second small boat, stairs to the swim step, and the entrance to the workshop, is not something that can be done as an afterthought. It needs to be on the concept plate from day one.

A final aspect to all this aft deck business. If we were so inclined, there is room for fishing–possibly a fighting chair. We could even work in an aft Matrix deck conning station so one of us could watch fish, angler, and boat, while maneuvering so the other could finish the fish boating process (perhaps an overly hopeful projection given a demonstrated lack of success in this regard). But then there would be the inevitable discourse on whose turn it was to clean the fish, and then hose down the stern. Maybe we’d better continue to buy from the locals.

*Note: This is the eighth post in this series about the FPB 78. You can access the posts in order by clicking on the dropdown menu from the “FPB 78″ button on the top menu bar.

Storage:

Although we have the same basement area we had on Wind Horse, this new FPB offers us more storage space than we have ever had in the past.

The workshop aft will accommodate the 12 plastic tubs of spare parts we carried on Wind Horse, with room left over.

There is space for 20 more of these bins under the bunks in the sleeping cabins, the equivalent of what we previously carried before in the basement for supplies when loaded to the maximum. These will be held in place with rails to keep them from sliding around.

The bunk faces are hinged on their bottom edge and fold down for access. The bins will then slide out from under the bunks. We think this system will be much easier to use than having to lift the mattress.

The last area of storage is something we’ve been after for years, a dedicated garbage locker. There are actually two lockers, entered from the swim step. The port side will house the aforementioned detritus, and the starboard has outboard fuel and other flammables. Both are ventilated to the  outside and sealed from the interior.

We have discussed the forepeak earlier. But it is worth reiterating that there is substantially more storage volume in this area than we have had in the past.

If we were hoarders, which we are not, we could double our storage area by aggressively utilizing the forepeak and workshop volume. What we are after is less dense, more easily accessed, and a better organized inventory that this basic volume makes possible.

*Note: This is the seventh post in this series about the FPB 78. You can access the posts in order by clicking on the dropdown menu from the “FPB 78″ button on the top menu bar.

Systems, Tankage, Range Under Power:

Our FPB 78 will be powered by a pair of L1066 Lugger diesels (based on the Deere 6068 series block). Lugger marinization, in particular their choice of fuel injection pump and turbo, gives us engines that allow cruising at eleven knots while turning approximately 1600 RPM, a very smooth and quiet place to operate these little diesels.

We will be able to carry as much as 4500 US gallons (17,000 liters) of diesel fuel, and 2675 US gallons (10,000 liters) of fresh water. This huge capacity is there for flexibility in choosing where and when to fuel, and to optimize weight and balance for various sea states. At eleven knots we have a range of over 6000 nautical miles. When we speed up to twelve knots we can still cross from the UK to the East Coast of North America, and back. If extra distance between fueling stops is required we can slow down to ten knots and stretch range to 8000 nautical miles. In the image above the center tanks are diesel, grey represents coffer dams, and the teal is fresh water.

Our new FPB Dream Machine will make use of the fresh air supply system, both passive and powered, developed for the Wicked FPB 97. Enormous air intakes, on the Matrix deck coaming and under the great room forward roof overhang, supply fresh air at anchor as well as underway.

This fresh air enters via a series of Dorade vents, two of which you can see in the foreground above. Using our standard closure system air flow is adjustable from inside the boat (as well as being able to seal these shut in heavy going). This will substantially reduce the need for air conditioning (we much prefer natural air flow to mechanical cooling). Add angled windows and large roof overhangs, and the warm weather ambiance improves even more.

When the breeze fails, there are a pair of exhaust fans at the aft end of the galley to pull fresh air in from the outside via the Dorade vents and through the great room.

The owner’s suite features two air conditioning units. The large unit is for pulling temperature down and removing humidity. The smaller unit can then be used on battery power during the evening to maintain temperature while moving air around.

Next we want to talk about a feature we really like, once again with its genesis in the Wicked FPB 97 design cycle. We refer to the systems room on the FPB 97. While we do not have the space for this in the smaller yacht, we have a layout that offers us similar functionality. We are creating a systems room using the port and starboard sides of the hallway between forward and aft sleeping quarters. The X-ray view above, taken from outside the boat on the starboard side looking to port, gives us a hint of what is inside.

Looking to starboard here, the inverters are revealed in their compartment, outboard of the stairwell. Major power distribution terminal strips, fuse blocks, and heavy breakers for winches, windlass, etc., all reside in this area. This locker is ventilated, lined in foam for noise attenuation, and the inverters are to be mounted on aluminum frameworks with soft isolation mounts.

To port is where the manifolds for the fuel, water, as well as the Kabola heater systems reside. Fresh water pumps and related plumbing is also in this area. We expect the aft bulkhead, and area low along the hull, to be occupied in this manner. The hatch shown provides access to the port stabilizer actuator. Otherwise, the area is available to us for storage. Odds are this will become a cold weather clothing locker.

Structure, Draft, Drying Out, and Cruising Grounds: 

We love the high latitudes, as well as thin water cruising, and the tropics. We want the option of cruising Antarctica, the Northwest Passage, and the tidal rivers of Europe, not to mention the Bahamas. To do this we need extreme toughness in the structure,

shallow draft (4.5 feet/1.35m),

and a design that allows for drying out with reduced risks.

We love this concept. It opens up all sorts of cruising grounds we would have never considered before. And think how easy it will be to clean the fins and propellers.

To this end, the hull framing and plating is our standard twice Lloyds Special Service Rule in stiffness.

Bottom plating varies from 24mm (one inch) on the grounding/gridding flat – shown above in purple – to 16mm (5/8”) in the turn of the bilge around the stabilizers down the center to the rudder posts – colored teal – with the rest of the bottom being 12mm (1/2”).

The stabilizer actuator mechanisms are over-sized for drying out and better impact resistance. Draft is 4.5ft (1.35m) to the bottom of the skeg.

You are probably wondering about the diagonal mullions on the forward windows. With the larger roof area over the great room and taller mullions in scale compared to the other FPBs, we felt some additional support was warranted. These give us a substantial increase in lateral (sideways) support with minimal impact on visibility. They are, in short, very efficient structurally.

Engine Room, Workshop:

The engine room, with its twin six cylinder Lugger diesels, has the volume for another classic, beautifully laid out arrangement with good access to all systems.

The Lugger diesels will drive 30”/750mm props via ZF 280-1 straight transmissions with a 3-1 reduction, and CV axles/thrust bearings, all of which adds up to efficient and quiet cruising.

The aft portion of the hull is now a workshop and storage area, and is accessible from the engine room,

or from the boarding platform.

Our layout has a large L–shaped workbench, a drill press, grinder, and belt sander, and twice the tool drawer space of the FPB 64.

We’ve got lots of room here for spares and supplies, both above and below the sole.

*Note: This is the sixth post in this series about the FPB 78. You can access the posts in order by clicking on the dropdown menu from the “FPB 78″ button on the top menu bar.