Father Son Project - Fibreglass Cathedral Hull

Discussion in 'Fiberglass and Composite Boat Building' started by scottm1976, Dec 9, 2018.

  1. scottm1976
    Joined: Dec 2018
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    Location: UK-Wales

    scottm1976 Junior Member

    Hi all,

    I am about to start a very steep learning process, my 11 year old son loves fishing (carp mainly but now sea) and it seems his natural progression has moved on to a purchase of an old 14-15ft cathedral hull fibreglass boat.

    I have done some research and there is a good local chandlery where I can go to have a chat about each project and buy bits I need however I want to do this properly from the start, does anyone here have any advice about anything that may help me plan things.

    I have stripped all of the metal work off the boat and removed the old board that housed the helm and separated the small cabin from the open deck, all deck panels removed. There are a couple of small cut-outs in the deck and which has let rain water in and soaked the foam (all covered up now with a tarpaulin and boat tilted to help drain any water), my first mini project is the deck; should the foam under the deck be replaced with new expanding foam or can I leave to dry out, the deck is sturdy and wouldn't say it needs to be replaced unless the foam doesn't dry out. Should the foam be replaced with a different material.

    Sorry its a long one but completely new and looking to gain as much info as possible as planning to start this after winter. I think with a lot of work and attention to detail this could be a nice little oat wen done, I just want to get it right.

    Thanks,
    Scott.
     

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  2. fallguy
    Joined: Dec 2016
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    fallguy Senior Member

    Buying a boat for taking a kid fishing is great thing.

    I have loved fishing since a young boy and why I like boats.

    For a wet boat, you want to make sure the boat has no core. Core, as in wood core. I doubt your does as most of those style we've seen on this website are solid glass. The 70s were a time of experimentation. If the boat has a wet core; it is almost impossible to repair.

    Once you know no core exists; you will probably want to remove the wet foam and refoam new. Take a small smple and see if it is wet through n thru. Wet thru means it is a more open celled older foam. Open celled foams will never dry out. Well, maybe 20 years in a heated climate controlled building. The new foams are closed cell and won't absorb water much.

    Just no idea to what foam you refer. You would be quicker to get the boat in the water physically removing any water or saturated foam.

    That boat is not made for rough seas at her beam; so avoid them.
     
  3. ondarvr
    Joined: Dec 2005
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    Location: Monroe WA

    ondarvr Senior Member

    There has always been a bit of confusion on flotation foam, there has never been an open cell product used for flotation, it only becomes more like an open cell product as it ages and the cell walls break down.

    Once the foam has become water logged it needs to be removed, there is no saving it.

    When the foam is wet then any wood in the boat is probably rotten also, this requires a total gut and rebuild.

    It can all be done, but it’s typically a labor intensive, time consuming and costly project.
     
  4. scottm1976
    Joined: Dec 2018
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    Location: UK-Wales

    scottm1976 Junior Member

    Hi,

    Thanks for the info, very helpful, I will do some research how to remove /replace the deck and remove all foam and replace with new, what type of foam is it,is it just any builders expanding foam or is there a specific for marine use.

    Looking at the 'stringers' I believe they are called running along the inside of the hull all seem to be rotten and they have been fibreglass over them so I believe I just cut the fibreglass open, pick out all the rotten wood with a screwdriver or similar and replace with new sections then re-fibreglass over. I am going to do what I can but where I need someone to help I will learn from watching them and so will my son as he will need to know how to do all this too.

    Sure I will get there but its finding all this information in the first place.

    Thanks.
     
  5. fallguy
    Joined: Dec 2016
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    fallguy Senior Member

    Typically the stringers when rotten are cut off just above the hull. Sometimes one at a time. And then new are made with timber and glass. Doing one at a time allows you to build the other the same height with less guesswork and avoids hull deforming.

    Often, when the stringers are rotten, the transom is as well. Check for rot at the transom at any through hulls or by removing say like motorwell drains or any other. Replacing a transom core is done at the same time as stringers and is easier to remove the inside skin and glass ans leave the outside glass and gelcoat alone.

    The labor and time might not be worth fixing this hull for a better one. Don't be afraid to say no to it. Or at least do the budget first. If you are doing this much work; it'd be better on a more seaworthy finished hull. Sometimes a free boat isn't free at all.

    You will need to acquire some cutting and grinding tools. Probably a wrecking saw; but use care not to hole the hull.

    If it were me, I'd probably say no to it if the transom core is rotten, which is usually the case when stringers are gone.
     
  6. scottm1976
    Joined: Dec 2018
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    Location: UK-Wales

    scottm1976 Junior Member

    I may have the terminology wrong, inside the cabin area there are horizontal lengths of wood fibreglassed in which may well be the battens to fix wood panels to and also the same type of battens horizontally on the side of the hull above deck. The transom area seems fine, what is the best way to check the transom for rot other than visually, if there is an issue then yes I would look for another project boat.
    DSC_0164.JPG

    Thanks for your help/advice, much appreciated.
     
  7. fallguy
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    fallguy Senior Member

    You can check the transom for rot at the garboard drain.

    If the sole(floor) is still in place; then you don't know if the hull stringers are rotten.
     
  8. scottm1976
    Joined: Dec 2018
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    Location: UK-Wales

    scottm1976 Junior Member

    Thanks, I will need to take the floor up and see what happens.

    Sorry to ask another question and this may sound stupid but is there a way to remove the deck and any do's/dont's.

    Thanks again.
     
  9. ondarvr
    Joined: Dec 2005
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    Location: Monroe WA

    ondarvr Senior Member

    In the last pic it looks like there a metal strip on top of the transom, remove it and inspect the wood. There also appears to be some type of material screwed to the outside of the transom, this can be a bad sign.

    Typically something is screwed to the transom because it’s in bad shape, then the new screw holes leak and make things worse.
     
  10. fallguy
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    fallguy Senior Member

    If you remove the sole/floor; it is best to do it and leave an edge all the way around, say like 2". The edge provides a guidance for the new replaced floor. You basically glue a tab of floor material underneath the 2" tab left behind and then glue the new floor atop. Of course, this assumes the sole is not rotten. If you encounter rot in the sole, remove only what is totally rotten and try to save the tab around the perimeter.

    Also, don't get too crazy with the saw, the hull is closer on the edges and easier to cut through.
     
  11. scottm1976
    Joined: Dec 2018
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    Location: UK-Wales

    scottm1976 Junior Member

    Hi,

    No metal strip on top of transom its where the top of the boat meets the hull.

    There was a mounting plate fitted which I believe was to protect the hull from damage when th engine was in place. The mounting plate was homemade and didn't really fit well so I took it off as I want to strip the boat back and repair so its a blank canvas, will have to take up the deck and have a good look just to make sure its all ok prior to putting money and time into it.

    Thanks.
     
  12. fallguy
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    fallguy Senior Member

    If they had the plate screwed on, check for rot in the screw holes. Use an awl or sharp tool and see if you can push down into the transom.. those holes will need repair anyway, so you can't really hurt the boat there

    I would still probably check down at the bottom further. You can do it from the inside. The screw holes might be rotten, but it might be limited to the top there.
     
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  13. SamSam
    Joined: Feb 2005
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    Location: Coastal Georgia

    SamSam Senior Member

    If there are no bolt or screw holes in the transom, which would be a wonderment extraordinaire, it wouldn't hurt to drill some just through the fiberglass so you can poke around with an awl to see if the wood is soft. They're easy enough to patch.

    Where fallguy says to leave a 2" strip of flooring around the perimeter is good, as the flooring is usually good on the edges and usually bad just in areas where deck penetrations were. Below the steering wheel where a seat pedestal is usually mounted is usually bad. If you just have smaller deck areas that obviously need repair, you can whack them out and that will give some access to assess damage under there, using mirrors and flashlights etc. If the only repairs needed are in areas like that, battens are attached to the underside of the deck that project a little into the cut out space, a new deck piece dropped in and screwed and glued to them, flush with the old deck, and then glassed over.

    You can't usually saw all the way to the sides, or conversely, it's easy enough to saw through or damage the hull trying to get there. Leaving the lip on the perimeter can save the labor of tearing out the edge of the old deck and all the grinding, remarking and attaching the new deck back in the same place (there is usually no ledge of sorts to set the deck on). What I have done is leave a roughly 3-4" strip of old decking on the perimeter and then screw and glue the new deck on top of the old deck , holding the new deck back from the sides an inch or so. The new deck edges are beveled, then screwed and glued to the old and then all is glassed over leaving a shallow gutter around the perimeter that drains back to the bilge pump. When cast netting or other wet activities the deck would stay comparatively unwet and the gutters would be small streams. Or you can cut it as fallguy says and put the new deck atop the old deck all the way to the sides and glass it in. Either way raises the deck the thickness of the new deck ( 1/2" or so) which can be a problem with molded liners, but it shouldn't be a problem in your boat. The new stringers will have be set that much higher (or higher yet for a crown in the deck) or with old stringers left in place, a strip of wood attached on top to bring them to the new level.

    Foam can be dug out in bits and pieces from under a deck, enough to let air circulate under there. You can replace it with the pink or blue home building foam cut in pieces and loosely put back in, trying to leave ventilation around wood members. I think flotation is better placed in sidewalls, as when swamped that will allow the boat to float level (albeit full of water) with you in it rather than to turn upside down and you have to struggle to climb onto the bottom and stay there. Ike from the Coast Guard would know about that stuff.

    One other thing to do is look at the bottom of the boat to see if any damage is there. Sitting on a trailer for a long time can introduce distortions, but with that type of hull (3 strong back vees)and seeing as how your trailer has bunks instead of rollers, it should be ok.

    Repairs and rebuilding usually take a fair amount of time and so winter is usually a good time to do them, to be ready for summer. The boy and the boat look like a real good match up.
     
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  14. scottm1976
    Joined: Dec 2018
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    Location: UK-Wales

    scottm1976 Junior Member

    Hi guys,

    Thanks for all the advice, its good to hear others explain in simple terms because until I start doing things sometimes its hard to understand, its a bit daunting but I am learning so that my son will grow up with the knowledge rather than have to start new like I am. We are both looking forward to this however it turns out with this boat it will be a good experience and he can't wait to get ti done and go fishing in his own boat that he helped to refurb.

    I will be spending a lot of time reading and watching YouTube for tips/advice, etc.

    Thanks again.
     
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