Plumbing the Depths, Or Not, With FPB 78-1

Engineering 533

You are looking at a sea-change in the way we do raw water for the engines.

In the past we have always employed a large through hull or partial sea-chest with a manifold below the waterline. All the engine room raw water consumers fed off this manifold. With a yacht design that will surf as easily as the FPB 78, the boundary layer aft combined with a negative pressure area means a manifold system will occasionally entrain air. The new system makes it much easier for the consumers to clear any air that gets ingested. But wait, it gets better. The valve is now well above the load waterline, so when it requires service it can be removed without hauling the boat. Furthermore, the forward section of the bilge is wide open and easy to clean.

Anybody have an idea why the smaller valve is there?

Engineering 531 2

That small valve is a drain from the aqua lift, so that when the boat is left for a few days humidity is reduced in the exhaust line.

Engineering 527

Moving forward now and looking at the raw water system in the forepeak. There are a pair of air con condensing coil cooling pumps, handling five compressors. There is also a washdown pump (top left), a bilge pump (not shown),

Engineering 537

and a pair of HeadHunter fresh water pressure pumps.

The trick is to install this stuff so the pumps can easily cope with their work load, while keeping the gear accessible and not ruining too much storage space.

Engineering 524

Here is a large grey water tank, probably a total waste of space and displacement, while adding a layer of complexity to the plumbing system. But rules require grey as well as black water, so here we are.

Engineering 526

Two of the eventual five air con compressors in this area. The compressors are isolated from their bases with isolation mounts, and then the framework is isolated from the structure tied to the hull.

Electrical 89

Lead electrician Deon Ogden is smiling because he has lots of room in which to install the electrical system. The bulkheads of the port systems room will eventually be covered with NAIAD black boxes, along with a host of Maretron N2K components.

Electrical 87

Starboard side inverters are now installed along with the auto transformer, as well as junction box for AC system high power switches and terminals (grey NMEA box).

Electrical 85

The main panel at the aft end of the great room is coming along quickly.

Interior 524

With wiring and plumbing runs now mostly complete, the prefabricated furniture modules will drop in short order.

Interior 509

The hull side lockers along the hallway to starboard of the owner’s suite have been patiently waiting their turn to shine. Once their doors are mounted and shelves installed, the first FPB 78 will rapidly start to look like a finished yacht..

Ali Fab 364

We will close with a photo of something we try really hard to avoid, but occasionally need to do. That is to rip out some perfectly good work in favor of something better. It is also a tale about how designs evolve. We are looking here at the inner transom, at the forward end of the swim step. It was originally designed at a steep angle: “coal chute” fashion for those of you old enough to recall this era. This approach allowed full headroom when entering the boat from the swim step, but cost deck space and crew cabin/lazarette volume. In the shower a couple of weeks ago there was a Eureka moment, and we realized this simply had to change to vertical. The advantages of deck space above and volume inside were such that it was worth the cost and disruption factor.

This also demonstrates one of the reasons we love unpainted aluminum. It is so easy to make changes…

Although FPB 78-1 looks far from finished, she is coming along very quickly. It won’t be until early next year when her protective furniture covers are removed and she is revealed in all her glory. But we can definitely see the light at the end of the tunnel.

Posted by Steve Dashew  (August 24, 2015)

12 Responses to “Plumbing the Depths, Or Not, With FPB 78-1”

  1. Michael Seng Says:

    Steve, forgive such a basic question but how are the furniture modules fastened to the hull (wood to aluminum)? I assume bolts through the lateral stringers to reinforced sections of the modules? If this is not considered proprietary photos would be appreciated. Certainly understand if that is the case. As always, thanks for taking us along!

  2. Steve Dashew Says:

    Hi Michael:
    Furniture is fastened in various way,some to aluminum channels which are glued to the sole, others with timber cleats, or mechanically fastened to the aluminum coamings.

  3. Bill Henry Says:

    I was wondering about the copper lines in the first photo. Could you explain?
    Thanks, Bill Henry.

  4. Steve Dashew Says:

    Morning Bill:
    As long as the copper is isolated from the aluminum, and not in a position where it can get wet and drip, it is fine. The advantage is amuch cleaner layout with less pressure drop and reduced risk of leaking connections.

  5. sean bryant Says:

    Hi Steve,

    Great pictures as always, few questions regarding your new water intake.

    1) Are you planning on adding any further supports to the “stand pipe” for the main SW intake, as it at the moment the weld would be highly stressed due to the bending moment put on it from the weight of the strainer?

    2) Presume your using some type of air eliminator on the top of the “stand pipe” to clear any air that builds up, how will this work as surely the system will be under vacuum as the SW has now got to be lifted?


  6. Steve Dashew Says:

    Hi Sean:
    Good eye for detail! Yes, there is to be a brace added to the standpipe off the nearby girder. Since we are pulling from above the waterline no air eliminator is possible. However, with a single consumer rated at 3m/10′ suction lift, this is not a problem. Elsewhere, with the pump manifolds below the WL forward and aft, we do make provision for a clearing line if it proves necessary.

  7. Joona Says:

    With the new vertical door design, how is access from aft deck to swim platform arranged?

  8. Steve Dashew Says:

    Hi Joona:
    Access to the swim platform is via stairs offset to port.

  9. Steve D Says:


    Bare with me, this does have to do with plumbing. Have you ever had any icing issues on deck in the high latitudes? I just finished re-reading Endurance and was reminded of Shackleton and the men taking turns chipping inches thick ice off the James Caird. Speculation was that icing took down the BERSERKER in the Ross Sea some years back – though there was also the issue of inexperience with them and a hurricane force storm which would have challenged most vessels

    I have seen heated decks on some polar research ships but they burn 5,000 gallons a day and have loads of wate heat. I am not sure how far south or north you think is reasonable in an FPB. Do you have spare heat that you are rejecting overboard anyway? It would require a bunch of pex tubing (or whatever) under the deck and above the insulation but might be useful if somebody is a glutton for punishment and really wants to push it in some yet to be built hull.

    By the way Rutgers put out an interesting video on a research cruise off the Antarctic Peninsula that some of the streaming services are carrying. You and your readers might enjoy.

  10. Steve Dashew Says:

    Hi Steve:
    Iced decks are a function of where and when you are exploring. We are not designed for icing or the increase in center of gravity that accompanies this unpleasantness.

  11. Ben Says:

    Hi Steve, very smart looking plumbing. And I’ve had similar problems with air building up in a sea chest on flatter, faster boats (maybe the bubbles running under the hull?), so it sounds like a good plan. Anyway with the standpipes what sort of wall thickness and type of tube are you using? I’ve always been slightly concerned about the difficulty of inspection of the inside of the standpipe from a corrosion point of view. Is a plastic liner a possibility or is this all a non issue? Cheers Ben

  12. Steve Dashew Says:

    Hi Ben:
    The basic rule of thumb is that the standpipe needs to be equal to the rule required bottom thickness in the area, if there is not a sea cock at the hull. In this case the pipes are roughly three inches/75mm ID with a 10mm 3/8″ wall. These are 5083 alloy so corrosion is not an issue. The flanged valves is easily removed for inspection.