pour foam, 14ft low sheer flats skiff ??

Discussion in 'Fiberglass and Composite Boat Building' started by Mark C. Schreiter, Aug 11, 2021.

  1. fallguy
    Joined: Dec 2016
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    fallguy Senior Member

    Well, the boat is already foam, so you sre probably close to pos buoyant. You can estimate it all if you want.

    But you like foam in the sole, so why not foam it in some.

    The key is designing for or against a wet bilge. For example, let's use a battery tray. If you buy a plastic battery tray and screw it down onto the sole, you will make penetrations into the sole and those penetrations may leak. If you have a fuel tank, you are required to have deck plates at the fill and pickup and those deck plates may leak someday. The battery can be set atop a 1/2" piece of foam that is bonded above the sole to make it impossible to go thru the sole. The deck plates leaking can be designed to flow down thru the bilge via limbers to a dry well. The dry well can be sealed with a piece of polycarbonate bedded in butyl. If there are any bilge leaks, the poly will develop condensation on it or you will see water in the drywell.

    You can still. limber a hull designed to be dry. You can use 6 mil plastic sheeting and light tubing for the drains. The tubing, say 3/4" cpvc can be holed. Then if you foam in, the foam doesn't go into the drain system, it floats above it all.

    Never foam after the sole is down; it must be done prior, then cut any excess and epoxy seal the cuts for the best chance at no ingress should water find a way.

    My designer advised a minimum of 12 ounce glass tapes atop the sole edges, but I'd use 1208.

    My build is all compartments, but this subject has gotten a lot of discussion on another board I frequent.
     
  2. Mark C. Schreiter
    Joined: Nov 2020
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    Location: Tampa, Fl

    Mark C. Schreiter Junior Member

    Although the designer of the plans was very responsive I just wasn't thrilled with what I paid for, so at this point id rather not mention names. The plans were meant for a "beginner" or first time builder and left out a lot of details and a lot of gray area for the builder. the BOM had obsolete materials listed and I ordered them from their company and then received a call "why did you order this material?", well that's what your plans told me to order. the plans were sent to me in the plywood version and there was a note that said a foam version was available. So I sent an email and received a 1 page word document that was the "foam version". At the same time I purchased 2 other plans. I wanted to study them all to determine what build would be best for me. all 3 plans were very different from each other. One of them had amazing detail and was 25 pages long where my build had little detail and was only 4 pages long and they were almost identical boats, just different lengths. I mean no disrespect I just expected more. I also don't believe in "industry standards". Make your own standards and forget what the "industry" does.

    To be fair I work as an engineer for a company who converts passenger commercial aircraft into cargo freighters. My job is literally reading engineering drawings and converting those drawings into workable task cards for the production folks to work off of. my drawings in some locations are down to .001 with a plus or minus tolerance of .001. I have to be extremely critical of the drawings because if an error slips by me, it could cause major structural issues or worse when the plane leaves. So my expectations of any sort of technical drawing are very high and its hard to check that at the door.

    I've also changed a few things and so out of respect, considering that, im sure he wouldn't be to happy of me claiming their his plans.

    I raised the sheer by a couple inches, he wanted i layer of 12 oz and 1 of 6 oz on both sides of just about every surface but it seemed way to weak so I opted for 2 layers of 1208 on each side. the plans also called for 5lbs 1/2in foam but I found a marine supplier who had 4lbs 1/2in for $800 less and from the mid point of the boat to the stern, the plans had it tapper towards the stern several inches and for some reason, not sure why, i reduced the tapper. Yes Im sure I changed the characteristics but i'll be standing up and casting a pole far more then I'll be cruising around so.....

    Anyway, below is a picture of the progress so far and a few of the build up. the pictures look worse then they are and i've since cleaned it up and trimmed and sanded the inside of the hull to prepare for bedding of the stringers and frames and all the tabbing. Ill also be glassing a layer of foam around the hull, a layer across the transom as well as the frames and the hull sides to support the decks and sole. but before all that I need to figure out the drainage and finalize the storage boxes, full tank and battery locations as the plans do not give locations or sugestions.

    -Mark


     
    bajansailor likes this.
  3. Mark C. Schreiter
    Joined: Nov 2020
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    Location: Tampa, Fl

    Mark C. Schreiter Junior Member

    So it goes back to the plans being for a "beginner" or first time builder. I assumed this type of information would be in the plans. I research and you know how that goes one guy says this is the only way to do and the other guy says if yo don't do it this way then the boat will blow up, crash and sink. my experience with composites is good but with boats, not so much. I think that's a big thing I'm missing and would probably help. at the end of the day I think the boat will work just fine, id just like to build it right.

    I thought about glassing in some foam blocks to raise up the battery and Ill do that for sure, well after I figure out where it goes. I think im gonna have to put that and the fuel tank closer to the bow. when I'm alone in my aluminum boat, batteries and fuel tank in the stern it takes a min to get on plane but with someone up front it jumps right up. good call on the deck plates as something similar would work for an inspection plates if I do not fill the cavities. I think at this point i'm opting for a portable fuel tank.

    thanks for the tips, they do help and give me a lot to think about.

    -mark
     
    Last edited: Aug 17, 2021
  4. fallguy
    Joined: Dec 2016
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    fallguy Senior Member

    I would cut limbers and mouseholes into any box that is below deck and not getting foamed in. That hole would allow water to make its way to bilge pump well.

    This does not look like a Mertens plan. He has been adapting his plans to foam.

    Designers do vary widely on the amount of detail provided. Building a dry or wet bilge is usually optional.

    My watertight compartments got rainwater in them! I had to use an oil changing pump to dry them. So, even a watertight compartment is only a theory if you don't seal the inspections well!
     
  5. fallguy
    Joined: Dec 2016
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    Location: usa

    fallguy Senior Member

    So, if the front area has hatches, then I'd put a mousehole on the center divider and the bulkhead would get one as well. You can cut them in with an oscillating tool.

    If, otoh the boxes are sealed, then don't bother.

    Anytime water will have any chance to get to the compartments, plan to make a pathway for it to the back and a pump well. It may never run, but you will be ready if fubar occurs.
     
  6. Mark C. Schreiter
    Joined: Nov 2020
    Posts: 69
    Likes: 12, Points: 18
    Location: Tampa, Fl

    Mark C. Schreiter Junior Member


    What do you mean by "limbers"?

    I'm really not planning on putting hatches in the bow or the stern for that matter, at least for now. I intend to use this as a casting deck for fly fishing and prefer a very clean snag free area. the second frame from the bow, at the sole in the center, I wanted to cut a larger hole for either the portable fuel tank or storage. I was thinking that id put a "deck" slightly higher than the sole and just have it drain to the sole, however, if I add drains from the other compartments to the bilge then i might as well forgo any of that and only make a deck for the fuel tank and have the storage area go all the way to the bottom of the hull? way to many options.
     
  7. fallguy
    Joined: Dec 2016
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    fallguy Senior Member

    ...part of the reason designers don't draw it all is so many options...

    A limber is a pathway for water through a bulkhead. Just like Tom n Jerry mouseholes. About an inch high and wide enough to allow water to flow. If you have any center stringer or floor, it gets cut as well at the union of the two.

    limber.jpg
     
  8. Mark C. Schreiter
    Joined: Nov 2020
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    Location: Tampa, Fl

    Mark C. Schreiter Junior Member

    I get that about the designers and options and so on and not to argue, if the plans are somewhat marketed for beginners I wouldn't think there would be so much left up to free will. Like where to place the fuel tank and bilge design and so on. maybe: if your using a 5 gal fuel tank, put it here or a 10 gallon, here and build xyz to support the battery. a few sentences, ideas or suggestions would go a long way. I'm sure i sound incompetent, i just want to avoid building an expensive paperweight.

    thanks for clarifying the Limber holes. and in fact in the plans notes it says "The limber holes in the center can be larger." and the next time it mentions them they are in a section of notes that says "limber holes not shown". then somewhere else it has a "typical" frame with what is called a "drain Hole" cut out of the center. logically I can now conclude that the "drain Holes" are the "limber holes".

    either way ill stop complaining, i think im on a better track now.

    thanks again

    -Mark.
     
  9. aaronhl
    Joined: Aug 2012
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    Location: Central Connecticut

    aaronhl Senior Member

    Here is the boat I am currently restoring, it has two outside and 1 middle sponson, it was built in 1990 and only the middle sponson had a drain plug at the transom, the two outside sponsons were completely shut with foam poured in them, onk well the outside sponson had a pluged drain which was like 2 inches above the bottom directly into the end of the foam...
    So I added balsa coreing to the outside sponsons, added not replaced, and then put a bunch of plywood in the boat, hopefully that will help it float because I dont really want to put much floatation back in and I left the sponsons open at the bow and a drain plug (and bilge pump) in each of the 3 sponsons...
    [​IMG]

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  10. sailhand
    Joined: Jan 2017
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    Location: australia

    sailhand Senior Member

    Have you considered extruded polystyrene sheets formed to your hull shape and then covering in light ply before laminating with glass and epoxy to form a solid one piece hull. You could run fore and aft stringers of ply on edge vertically to strengthen the build. This could be thick enough to make the craft self draining whilst having centralised storage between the stringers down to the ply on the keel. You would need to have a raised coaming forming say a seat or console or both. I am not sure how effective the extruded polystyrene would be with the ply covering as far as compression loading is concerned. The ply should prevent point loading and the stringers help with the sheer stresses. If you have access to a cnc router and 3d software that would make shaping the polystyrene a breeze and you could also accurately cut the ply to laminate the foam. There are some incredible contact adhesives these days that you could use to assemble the ply foam components and then a single layer of glass around the lot. Just a thought!!
     
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