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Discussion Starter · #1 ·
First time poster but have done a lot of lurking.

I’m currently removing the deck and stringers/foam from an old 14 foot stumpknocker. I plan to totally rebuild the stringer and the floor, along with removing original storage hatches and replace with a back deck and front deck to serve as casting platforms and additional storage. I’ve done a lot of thought about materials and Final design but more hung up on materials. I have experience with poly And Epoxy resin and some fiberglass work from shaping surfboards but no experience with boat construction.


Pretty dead set on working with Epoxy resin. I was debating between different corn materials But I am leaning towards Okume Half inch ply for the deck, as far as glassing schedule goes I’ve read a lot of people using anything from multiple layers of 6 ounce, all the way up to 17 ounce Biax. When glassing in the stringers keeping in mind that this is going to be my inshore creeks and flats boat what glassing schedule would you recommend? I was thinking about cementing The stringer to the hull with Thickened epoxy Then layover two layers of 10oz biax with the top layer extending a few inches pass the shorter one. Is this schedule too lite/ or to heavy? What glass schedule would you/have you used on similar size and function boats.


Regarding materials I’ve looked out west system, system 3 and a few other Epoxy brands but I’m not decided on one. Granted this project is going to take me into fall and winter in north east fl, i’ll be working in anything between 50 and mid 70° weather But I plan on glassing around days where the nightly low stays above 60. I’m trying to find a cost-effective Resin with a medium to low viscosity for ease of application and a bonus would be a medium speed Hardner(most are just slow and fast) also would I actually need to go with a fast hardener on a 65 degree day.


Using the half inch marine okume ply what glassing schedule would you recommend for the deck and casting decks. I was originally thinking two layers 10 ounce biax just like the stringer and for the underside possibly going with a few good layers of epoxy to seal around bottom and edges, how would y’all do it? I thought I could get away without bottom glass because I don’t plan on putting any screw holes in the deck, was planning on using Thickened epoxy to bond of the deck to the stringers.


What glass weight would you recommend?


What epoxy company/harder speed?


In addition, I’m contemplating using foam core like divinycell or pvc foam For the aft and rear deck, would the weight being saved by a composite Be that significant? Also how do composite foams span gaps with load? Do they need more/less or equal bracing
 

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I have used West systems ,and on more current projects, Jamestown distributors epoxies with out complaints. The West system epoxies have an extra-slow hardener(Jamestown does not) and tends to sag more than the Jamestown. You have to be quick with both of them when mixing large amounts. All of my boat projects, the wood was the structure and I used lightweight cloth as a protection and wearing surface. Someone else will have to advise you on structural glass lay up. I did glass the bottom of my floor deck for extra protection from moisture. Hopefully this answered some of your questions
 

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First time poster but have done a lot of lurking.

I’m currently removing the deck and stringers/foam from an old 14 foot stumpknocker. I plan to totally rebuild the stringer and the floor, along with removing original storage hatches and replace with a back deck and front deck to serve as casting platforms and additional storage. I’ve done a lot of thought about materials and Final design but more hung up on materials. I have experience with poly And Epoxy resin and some fiberglass work from shaping surfboards but no experience with boat construction.


Pretty dead set on working with Epoxy resin. I was debating between different corn materials But I am leaning towards Okume Half inch ply for the deck, as far as glassing schedule goes I’ve read a lot of people using anything from multiple layers of 6 ounce, all the way up to 17 ounce Biax. When glassing in the stringers keeping in mind that this is going to be my inshore creeks and flats boat what glassing schedule would you recommend? I was thinking about cementing The stringer to the hull with Thickened epoxy Then layover two layers of 10oz biax with the top layer extending a few inches pass the shorter one. Is this schedule too lite/ or to heavy? What glass schedule would you/have you used on similar size and function boats.


Regarding materials I’ve looked out west system, system 3 and a few other Epoxy brands but I’m not decided on one. Granted this project is going to take me into fall and winter in north east fl, i’ll be working in anything between 50 and mid 70° weather But I plan on glassing around days where the nightly low stays above 60. I’m trying to find a cost-effective Resin with a medium to low viscosity for ease of application and a bonus would be a medium speed Hardner(most are just slow and fast) also would I actually need to go with a fast hardener on a 65 degree day.


Using the half inch marine okume ply what glassing schedule would you recommend for the deck and casting decks. I was originally thinking two layers 10 ounce biax just like the stringer and for the underside possibly going with a few good layers of epoxy to seal around bottom and edges, how would y’all do it? I thought I could get away without bottom glass because I don’t plan on putting any screw holes in the deck, was planning on using Thickened epoxy to bond of the deck to the stringers.


What glass weight would you recommend?


What epoxy company/harder speed?


In addition, I’m contemplating using foam core like divinycell or pvc foam For the aft and rear deck, would the weight being saved by a composite Be that significant? Also how do composite foams span gaps with load? Do they need more/less or equal bracing
Call Reid at Boat Builder Central in Fort Pierce and he'll set you up with everything you'll need. 772-742-8538. I've built 4 of their plans, and have used both their Marine Epoxy brand, and the System 3. Both are non blushing and great to work with, with the System 3 being a lot more expensive. All of my decks are 3/8" Okoume with 1 layer of 6 oz. woven on top, and the underside coated with epoxy. If you frame the deck adequately, 3/8" is more than enough, in fact all of my cockpit soles are 1/4", but are fully foamed, so there's added support from the foam being shaved off flush with the stringers and framing. 3/8" ply is all you need for stringers, glassed in with 6" wide 12 oz. biaxial, and fillets made with epoxy thickened with wood flour. Good luck with your build. Mike
 

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@seapro17sv said it!

Use 3/8" instead of 1/2" ply, 6oz fabric is more than enough for the top (I also used it on the underside of the decks because, why not, its pretty light). 1 layer of 12oz biax is more than enough for the stringers (and any transom tabbing you may have to do).

I like MarinEpoxy from BBC as well, but others on this site also enjoy working with the FGCI epoxy...

Woodflour is my choice for thickening epoxy for fillets/bedding material when you go to bed stringers/deck to stringers...

Good luck!
 

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Discussion Starter · #5 ·
Call Reid at Boat Builder Central in Fort Pierce and he'll set you up with everything you'll need. 772-742-8538. I've built 4 of their plans, and have used both their Marine Epoxy brand, and the System 3. Both are non blushing and great to work with, with the System 3 being a lot more expensive. All of my decks are 3/8" Okoume with 1 layer of 6 oz. woven on top, and the underside coated with epoxy. If you frame the deck adequately, 3/8" is more than enough, in fact all of my cockpit soles are 1/4", but are fully foamed, so there's added support from the foam being shaved off flush with the stringers and framing. 3/8" ply is all you need for stringers, glassed in with 6" wide 12 oz. biaxial, and fillets made with epoxy thickened with wood flour. Good luck with your build. Mike
@seapro17sv said it!

Use 3/8" instead of 1/2" ply, 6oz fabric is more than enough for the top (I also used it on the underside of the decks because, why not, its pretty light). 1 layer of 12oz biax is more than enough for the stringers (and any transom tabbing you may have to do).

I like MarinEpoxy from BBC as well, but others on this site also enjoy working with the FGCI epoxy...

Woodflour is my choice for thickening epoxy for fillets/bedding material when you go to bed stringers/deck to stringers...

Good luck!
Thanks for the help, I was suprised to find out after ripping out the deck my boat had only one stringer! Now that’s probably common but on all boat build I watched/studied I never saw a boat with less than 2, I plan on building some bulkheads whose only purpose would be to support the deck, does this sound like a bad idea? Also I’m probably going to use pour foam once all gaps and edges have been sealed on the deck before the top skin is applied IF done correctly does that self expanding foam provide any structural support for the deck
 

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Thanks for the help, I was suprised to find out after ripping out the deck my boat had only one stringer! Now that’s probably common but on all boat build I watched/studied I never saw a boat with less than 2, I plan on building some bulkheads whose only purpose would be to support the deck, does this sound like a bad idea? Also I’m probably going to use pour foam once all gaps and edges have been sealed on the deck before the top skin is applied IF done correctly does that self expanding foam provide any structural support for the deck
Most of the expanding 2 part foam that most use for filling in voids is 2lb. Here is the label from US composites

Product Information:
Free Rise Density: 2.0 lbs per cubic ft.
Expansion Rate: Approx. 25-30x Liquid Volume
Buoyancy (flotation): 60 LBs per Cubic Ft.

*Physical Properties:
Parallel Compressive Strength: 40 psi
Tensile Strength: 30 psi
Shear Strength: 30 psi
Flexural Strength: 50 psi

To answer your question, it is not really intended to provide structural support. You should use ribs to help. here is an example of pre-foam/post-foam of an area that is about 4ft x 6ft


 

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Discussion Starter · #7 ·
Ok
Most of the expanding 2 part foam that most use for filling in voids is 2lb. Here is the label from US composites

Product Information:
Free Rise Density: 2.0 lbs per cubic ft.
Expansion Rate: Approx. 25-30x Liquid Volume
Buoyancy (flotation): 60 LBs per Cubic Ft.

*Physical Properties:
Parallel Compressive Strength: 40 psi
Tensile Strength: 30 psi
Shear Strength: 30 psi
Flexural Strength: 50 psi

To answer your question, it is not really intended to provide structural support. You should use ribs to help. here is an example of pre-foam/post-foam of an area that is about 4ft x 6ft


Ok definitely going with the ribs for support. Most of the Pour foam insulation I have seen has been done by cutting small holes into a previously layed deck(minus final top layers of glass) in your picture was it done this way then the deck was removed, or is there another method to a flush and level foam will before the deck was applied?
 

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Ok

Ok definitely going with the ribs for support. Most of the Pour foam insulation I have seen has been done by cutting small holes into a previously layed deck(minus final top layers of glass) in your picture was it done this way then the deck was removed, or is there another method to a flush and level foam will before the deck was applied?
No, deck was off before foam was poured (this was a rebuild of an old hull). To make it level, I used an undercut saw and a board to check for levelness, once the foam was cured of course. You don't have to get it perfect, just close enough. But I do suggest a coat of neat epoxy to the exposed foam before bedding the deck.

here is what an undercut saw looks like - they're cheap - less than $10 at harbour freight/HD/Lowes
 

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oh and once you have a 3/8" plywood sheet covered in 6oz glass on both sides, it is pretty stiff, and you most likely will not need any additional support from the foam. I once read that spans of 30" or more were easily achievable with 3/8" ply and 6oz on both sides (never tested this so don't hold me to it).
 

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Discussion Starter · #10 ·
oh and once you have a 3/8" plywood sheet covered in 6oz glass on both sides, it is pretty stiff, and you most likely will not need any additional support from the foam. I once read that spans of 30" or more were easily achievable with 3/8" ply and 6oz on both sides (never tested this so don't hold me to it).
Ok great information, so a thin coat of epoxy won’t welt the foam? I like the idea of pouring the foam prior to setting the deck so you have more control
 

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Ok great information, so a thin coat of epoxy won’t welt the foam? I like the idea of pouring the foam prior to setting the deck so you have more control
MOST urethane foams available at boat building suppliers and MOST epoxies available at those suppliers are compatible. Its easy enough to test a piece of the cut off foam to be sure.
 
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