[Wasy_]

Hey guys, Learning all i can about redoing an old boat. I have a question about pour foam and coring. From my understanding there are 2 ways to do it.
1. Only core the Freeboard section of the boat. Then pour foam between the stringers. Level foam, Glass over foam. Install Deck.

2.Core bottom and sides of boat. and instal deck on top of the stringers. and have essentially a hollow hull.

All the searches I have seen do not really address this. I know the downside to foam is that it will absorb water if exposed. But aren't all new boats filled with foam?

If it helps I am building what i believe to be a Wenzel 14 and i have a thread in the bragging spot about it. Just thought i would post here to get the question answered.

Right now with the way the hull is setup, its straight glass. no core except for the transom. and does not drain for shit. If you catch a bad wave and catch a decent amount of water this thing is going down. So id like to raise the floor to be self bailing, and possibly even install a bilge for extra punch god forbid i take a nasty wave. Along with adding coring for rigidity. ( i wouldn't be out if conditions were not safe for the boat, but safety is a priority as this boat may become what my nephews learn boating basics in.)

Thank you for your input!
and here! I drew reference pictures while at work lol

 

[yobata]

If you are going to use 2 part expanding foam, just make absolutely sure that area is completely water tight (encapsulated) and use epoxy resin which is more impervious to water intrusion than polyester resin.

Also, you stringers look huge! For a small boat like this, you could do two smaller stringers...

 

[Wasy_]

If you are going to use 2 part expanding foam, just make absolutely sure that area is completely water tight (encapsulated) and use epoxy resin which is more impervious to water intrusion than polyester resin.

Also, you stringers look huge! For a small boat like this, you could do two smaller stringers...

Yea they are huge. Lol nothing's to scale. I beleive what I see most guys useing for stringers is either 3/4 inch or 1 inch for the stringers?

So you are telling me if I use pour foam I do not have to core the bottom of the hull?

 

[BassFlats]

Why do you feel you need to core the sides.

 

[Wasy_]

Why do you feel you need to core the sides.

Simply because that's what i see other guys doing. And the added rigidity to the hull i guess?
I am really new to this. so if anyone knows a better/ simpler/ more productive way of doing this i am all ears!
Thanks guys

 

[yobata]

Simply because that's what i see other guys doing. And the added rigidity to the hull i guess?
I am really new to this. so if anyone knows a better/ simpler/ more productive way of doing this i am all ears!
Thanks guys

if you add bulkheads, rod holders and gunnels, you will also make the sides more rigid

 

[yobata]

So you are telling me if I use pour foam I do not have to core the bottom of the hull?

I am not really saying either because I don't know your boat's condition. You could (as I did), add a layer of fiberglass to the entire bottom of the boat (I used 12oz biax). This could be enough to stiffen up the bottom (I am also assuming that your boat originally came with bench seats which also add rigidity to the bottom and sides). On my re-build, that single layer of 12oz biax was not enough and under power, the bottom of the boat would flex. I then added 2 stringers (1x2 southern yellow pine in my case) and ribs to support a "sole" / cockpit deck. I chose to add foam in all the spaces/cavities in between the stringers and ribs before adding a "sole"/ cockpit deck. But all of this depends on the condition of your boat. You absolutely CAN core the entire thing, but sometimes in smaller skiffs like this, it isn't worth the effort/cost.

See the link in my signature for pictures of stuff I describe above.

 

[BassFlats]

You are probably going to have a front deck and some sort of seat tying the sides in. You will be surprised ,when you fasten the floor to the sides, how ridgid the sides get. Wait till then before deciding whether you need to stiffen up the sides.

 

[Wasy_]

I am not really saying either because I don't know your boat's condition. You could (as I did), add a layer of fiberglass to the entire bottom of the boat (I used 12oz biax). This could be enough to stiffen up the bottom (I am also assuming that your boat originally came with bench seats which also add rigidity to the bottom and sides). On my re-build, that single layer of 12oz biax was not enough and under power, the bottom of the boat would flex. I then added 2 stringers (1x2 southern yellow pine in my case) and ribs to support a "sole" / cockpit deck. I chose to add foam in all the spaces/cavities in between the stringers and ribs before adding a "sole"/ cockpit deck. But all of this depends on the condition of your boat. You absolutely CAN core the entire thing, but sometimes in smaller skiffs like this, it isn't worth the effort/cost.

See the link in my signature for pictures of stuff I describe above.

Saved your build thread. Thank you. A ton of similarities with my hull. Yes, the weight concern of coreing the entire hull concerned me especially since i am going with marine plywood on this. for 2 reasons. 1. I dont feel like spending a ton of money for my first build. 2. Up where i live i cant seem to find a composite supplier locally.

 

[Wasy_]

You are probably going to have a front deck and some sort of seat tying the sides in. You will be surprised ,when you fasten the floor to the sides, how ridgid the sides get. Wait till then before deciding whether you need to stiffen up the sides.

Thank you. This is why im asking these types of questions here. i did not think those would stiffen it up enough. But with transom is redone, 2 bulkheads added, and stringers. It would probably hold up fine. and at tat point i find out its not i could always glass in some coring to the sides correct.

 

[BassFlats]

Here's a couple of pics of a bassboat hull I converted to a tiller flats skiff. No foam below the floor. View attachment 107370

 

[Wasy_]

Here's a couple of pics of a bassboat hull I converted to a tiller flats skiff. No foam below the floor. View attachment 107370 View attachment 107372

Thank you. Did you finish it yet? Or just start it?

 

[BassFlats]

I finished it last year.

 

[DuckNut]

@yobata gave you good advice and so did @BassFlats .

You have two issues here which need addressing. 1) stiffness and 2) flotation. If you want it stiffer a layer of 1708 will be plenty on the gunnels. You can add core but not needed.

You need to find places to stuff some flotation foam. If I am right it was under the seats in the original. So, now where can you hide it. Build a walking tunnel like bass did and put it under there. Doing that you will stiffen the sides without anything additional. If not you will need to put it under the floor.

 

[PG350]

Did you cut out the seats and deck yet? If not dont cut them all the way out, just cut them down to the level of your floor and use the as partial stringers. This will save material and keep the shape of the boat.

 

[Wasy_]

@yobata gave you good advice and so did @BassFlats .

You have two issues here which need addressing. 1) stiffness and 2) flotation. If you want it stiffer a layer of 1708 will be plenty on the gunnels. You can add core but not needed.

You need to find places to stuff some flotation foam. If I am right it was under the seats in the original. So, now where can you hide it. Build a walking tunnel like bass did and put it under there. Doing that you will stiffen the sides without anything additional. If not you will need to put it under the floor.

I'd like to install a deck and foam underneath that.

 

[Wasy_]

Did you cut out the seats and deck yet? If not dont cut them all the way out, just cut them down to the level of your floor and use the as partial stringers. This will save material and keep the shape of the boat.

You are 100% correct. I have not started cutting anything out yet. I will definitely be doing this.

 

[DuckNut]

I finished it last year. View attachment 107392

I just noticed.

That is a first for me. This is the first time I ever saw a house painted to match a boat.

 

[DuckNut]

I'd like to install a deck and foam underneath that.

Go read the other thread about foam and you will know what to do from it.

 

[BassFlats]

Apparently I like green Ducknut.