Fibreglass boat floor replacement - do I need to use fiberglass?

[ShoestringMariner]

Hey everyone, I dragged home a 16’ Peterborough Mistress bowrider with a gutted interior (seats and floors removed) . Essentially It only needs needs floors, carpet and seats. I bought it for the trailer and motor and was going to save a few pieces off the boat and take it to the landfill or give the hull away . But because the transom looks really solid and the hull is clean, I started considering putting it back together and playing with it for a while. It looks like a fast, fun boat rated for up to 70hp

So here’s the thing; I’m a tin boat guy. I know nothing about using resin and cloth and truthfully, I don’t want to get into that.

Now my question is; is installing a wooden floor with adhesive applied with a caulking or sausage an option? The plywood floor supports are shot, but I was thinking of bending aluminum channels to suit and adhering them (and the plywood) with some sort of high bond product.

Thoughts?

If there are any restoration purists out there, please don’t slag me if this is a shoddy or an unorthodox type of repair. If my idea will work and extend this boats life by 5-15 years, I’m happy with that. (this boat will be day use, trailer/dry stored)

If this is something that just won’t work, please say so. An explanation why not would be appreciated. If adhesive will work, please let me know what’s the best type to use?
Thanks in advance

 

[racerone]

Find-----WEST SYSTEM EPOXY----repair guide.-----Available FREE at most places that sell these products.----West System epoxy is not cheap.----I am using that on a boat that hopefully the grandkids will say.------" Grandpa built / fixed this boat, no wood in it and it will never break or rot again "

 

[ShoestringMariner]

Find-----WEST SYSTEM EPOXY----repair guide.-----Available FREE at most places that sell these products.----West System epoxy is not cheap.----I am using that on a boat that hopefully the grandkids will say.------" Grandpa built / fixed this boat, no wood in it and it will never break or rot again "

Thank you, yes I have seen some write ups about the West system. The thing is and perhaps true to my user name, I don’t want to spend a lot of money on this boat. It’s not worth it for resale. By the time I put floors carpet seats into it, I will have spent a good chunk of change. I worry that I’ll be Spending more than the boat is worth for resale. I don’t care if this boat doesn’t last past 10 years. Realistically, a five year lifespan will suit me fine as I will have moved on to something else likely bigger and my kids will probably have moved on from it as well.

So is there a real cheap way of doing this without getting into the messy fiberglass/resin/cloth type project? Probably why I like aluminum boats. Screw the plywood down put carpet of vinyl on it, boom done.

EDIT; oh, I see the West Six10 thickened epoxy tube. That’s what I was thinking. Set the plywood onto a thick bead of adhesive and let cure. The plywood would be pre-sealed by a varnish based preservative with a spar varnish topcoat. Way more than the factory would have given it.

 

[Chris1956]

Epoxy is not necessary for that type of repair. You do need to use polyester resin and cloth, however. Resin and polyester putty are available at marine stores and even the Home Despot. Cloth is available usually only at marine stores.

Replace any rotten stringers or frames with dry, solid pressure treated dimensional lumber, of the same size as the original. Sand all fiberglass until clean and dry, before installing the stringers. Mix up some polyester putty and use it to bed (stick) the stringers and frames to the hull. Use some strips of cloth, saturated with catalyzed poly resin to on the sides of the stringers and frames further attach stringers and frames to the hull. Pour 2 part foam between the stringers and when cured, trim flush.

Dry out some 1/2" pressure treated plywood for the deck (floor). Cut it to size and lay some strips of saturated fiberglass cloth on top of the stringers and frames. Now screw thru the decking into the stringers and frames with SS wood screws.
Cover the deck with 2 layers of light fiberglass cloth or one layer of light fiberglass mat. Saturate it well with resin and let her harden.

Now install carpet seats etc, as you like.

Piece of cake....

 

[ShoestringMariner]

Epoxy is not necessary for that type of repair. You do need to use polyester resin and cloth, however. Resin and polyester putty are available at marine stores and even the Home Despot. Cloth is available usually only at marine stores.

Replace any rotten stringers or frames with dry, solid pressure treated dimensional lumber, of the same size as the original. Sand all fiberglass until clean and dry, before installing the stringers. Mix up some polyester putty and use it to bed (stick) the stringers and frames to the hull. Use some strips of cloth, saturated with catalyzed poly resin to on the sides of the stringers and frames further attach stringers and frames to the hull. Pour 2 part foam between the stringers and when cured, trim flush.

Dry out some 1/2" pressure treated plywood for the deck (floor). Cut it to size and lay some strips of saturated fiberglass cloth on top of the stringers and frames. Now screw thru the decking into the stringers and frames with SS wood screws.
Cover the deck with 2 layers of light fiberglass cloth or one layer of light fiberglass mat. Saturate it well with resin and let her harden.

Now install carpet seats etc, as you like.

Piece of cake....

Thanks Chris, I understand this is the traditional way of doing the floor replacement. Could I ask what sort of problems I could run into by doing the repair the way I had in mind?

I don’t know fibreglass at all. Mixing up patties and resin’s and all that stuff is totally foreign to me. And by my way of thinking seems to be quite a lot of work and expense. I hope I don’t come across as cheap or lazy (although my username definitely implies cheap) The situation is one where I have a lot of projects and only so many funds to spread around.

I’m currently replacing the floors in my Starcraft super sport ( aluminum hull) which explains where my head is in regards to simply “fastening with adhesive“ to install the floor to the fibreglass hull in the Peterborough.

I was thinking that my approach would be much cheaper, significantly less messy and involved, no learning curve and a faster way to get this boat completed.

If the answer is as simple as “there’s no way any kind of adhesive will fasten floor stringers and floorboards to fibreglass hull” or “that bond may break apart in rough waves etc.” Then I have a choice to forge through the project or part it out and scrap the hull.

If the answer is “yeah, it’s a bit unorthodox, but that might get you 5 to 10 years service life”, then I’ve got something to think about.

I suppose I could say that I’m looking for an easy way to save this boat. I have no attachment to this boat, I just felt it was too good to take to the landfill.

 

[Baylinerchuck]

The real strength in bonding wood, (non-pressure treated) to a fiberglass hull is tabbing it to the hull with fiberglass. Simply bedding wood into glue just isn’t going to get it done. That bond will almost certainly fail as the fiberglass hull constantly flexes against the pressure of water, trailering, and pounding waves. In a fiberglass boat, the structure is always tied together with the hull with fiberglass. This is the mechanical connection, like rivets in an aluminum boat. You wouldn’t simply glue an aluminum boat together without rivets, and you shouldn’t glue a fiberglass boat together without fiberglass. Also add to the equation that flotation foam very often adds to the structure of the boat, adding rigidity and further bonding all the structural components together to include the deck. All this to say that a boat that is only glued together would be incredibly unsafe in my opinion.

 

[Scott Danforth]

you cant walk upright with half your spine missing...... consider the stingers hull and deck the spine of your boat.

 

[ShoestringMariner]

Ok understood, thanks guys.

 

[ShoestringMariner]

Hey guys, can I ask if the floatation foam needs to be “pour” in? Or can I use the dense closed cell foam cut to size? (Styrofoam SM - does not absorb water)

the thing with pour in foam is that I don’t know how much to add to get a level surface close to the underside of the floor. If I pour in too much, I’ll have to shave it down which means it is now susceptible to water logging because I’ve exposed the foam cells(?) The whole process seems trial and error and about as effective as pushing a rope in regards to achieving accuracy

 

[jbcurt00]

Depends, does a 16ft Peterborough depend on the foam for structural/torsional rigidity?

What foam was in it originally? Since you got it gutted....

 

[ShoestringMariner]

I bought it gutted. The remnants of foam appear to be pour in. Not sure if the factory intended on the foam being structural or just a more cost effective means of manufacturing.
it’s a very shallow hull if that helps. The boat in the pic is not mine but the same hull.

 

[ShoestringMariner]

Found a pic. This one is mine. Shows how flat and shallow the hull is at the back.

 

[jbcurt00]

The short answer is pour in because we cant be sure it wasnt intended for more then simple flotation.

Foam is likely cheaper per SqFt then additional layups of glass for the bottom of the hull, plus its labor and as its required to float, 2 birds 1 stone.

Most that pour foam do the best they can to fill it w foam AFTER the deck goes down thru 3 or 4in holes. Trade off is how do you KNOW 100% of every area is filled completely. Ideal pour temps/conditions for maximum expansion is important.

 

[ShoestringMariner]

The short answer is pour in because we cant be sure it wasnt intended for more then simple flotation.

Foam is likely cheaper per SqFt then additional layups of glass for the bottom of the hull, plus its labor and as its required to float, 2 birds 1 stone.

Most that pour foam do the best they can to fill it w foam AFTER the deck goes down thru 3 or 4in holes. Trade off is how do you KNOW 100% of every area is filled completely. Ideal pour temps/conditions for maximum expansion is important.

Thank you. Is this foam considered low expansion? I’d hate to have it bulge the hull, floor etc

 

[todhunter]

The stuff I'm using (from US Composites) says it expands 25x - 30x depending on temperature. Calculate your volume in cubic feet, divide by 30, and mix up / pour that amount. If it's not enough, you'll have to top it off. If it's just a little too much, it shouldn't add THAT much pressure.

 

[ShoestringMariner]

The stuff I'm using (from US Composites) says it expands 25x - 30x depending on temperature. Calculate your volume in cubic feet, divide by 30, and mix up / pour that amount. If it's not enough, you'll have to top it off. If it's just a little too much, it shouldn't add THAT much pressure.

Thanks. I don’t want a disaster on my hands. I’ve used the “low expansion” window and door trim and had expansion issues)

 

[mickyryan]

if you cut two holes with holesaw in each cavity it will allow excess foam to come out then you plug those holes and put your last layer of csm or 1708 across floor and done. you need to use at least 2lb closed cell foam or it will absorb water, in other words great stuff not gonna do it for you and either is Styrofoam because Styrofoam isnt good for boats coast guard dont care for it either.

 

[kcassells]

if you cut two holes with holesaw in each cavity it will allow excess foam to come out then you plug those holes and put your last layer of csm or 1708 across floor and done. you need to use at least 2lb closed cell foam or it will absorb water, in other words great stuff not gonna do it for you and either is Styrofoam because Styrofoam isnt good for boats coast guard dont care for it either.

Ya know Mick I was waiting to see how he was going to pour the foam and the type of foam he used before.
.1. Marine foam is not the same as can foam.
2. Elevate the boat, ...blah blah blah and let me see how you fill in the blanks.

 

[froggy1150]

When i poured my foam i had left gaps in the tabbing where floor meets hull as well as the holes for poaring foam. The gaps were 4-6" every 2' or so placed strategically so the air could escape and let the foam go to the sides of the hull instead of just foward. Also had lots of scrap wood and weights to put on top of foam once it started coming out. I also lifted the bow as high as i could get it. The back of the trailer was on the ground, both sets of wheels were not and the tongue was about 5' up. 21' cabin cruiser.

 

[Chris1956]

Gee, pour the foam before you install the decking. Use a long knife to cut the foam flush to the top of the stringers. Why bother with strategically placed holes that you have to plug?

Then, lay some strips of polyester resin saturated cloth on top of the stringers and screw the new decking into the stringers with SS wood screws. Now put 1 heavy layer of cloth or 2 lighter layers of cloth over the deck and add polyester resin. Not too complicated...