Replacing floor and transom in 1986 Sylvan 17' aluminum v-hull

[Lak2004]

I am currently in the process of replacing the floor in my 87 sylvan 17' fishing boat. I noticed the transom was also completely rotten and so I will be replacing that as well. For the floor I am going to tear out the old (keeping intact for template) and replace with MDO. Is 1/2" good enough or go 5/8" or 3/4"?

Should I use MDO for the transom and use 3 pieces of 3/4" to be 2.25" thick total? The motor is an outboard Mariner 80.

Also, for under the floor I would like to do foam blocks to make the ride smoother. I am on a serious budget here and I was thinking about using spray foam insulation. Rather than spray it directly into the hull I was thinking about making my own blocks by spraying it into a cardboard box and pulling them out when dry. Any other ideas on doing the foam blocks?

This is the first time I have messed with a boat and I cannot wait to get it done.

Thanks and any help is greatly appreciated!

 

[rirory]

Re: Replacing floor and transom in 1986 Sylvan 17' aluminum v-hull

I am on my 6th or 7th aluminum re-doo now. I would make the transom the same thickness it was. The one i did this weekend was 2 pieces of 3/4 & 1 piece of 3/8--glued and ss screwed then painted then epoxied. I always use 3/4 exterior plywood on my floors and use 2 coats of epoxy to seal it before i carpet it. It will last 15 years. No P T wood ever in aluminum boats. For foam ---Use pool noodles or blue/pink sheet foam they sell at the box stores.

do not rush--- my last one (1966 20' chrysler polara 254-chronicled here) took 2 years.

there are tons of posts here to help you and do not hesitate to ask ??????'s

good luck

ri rory

 

[jigngrub]

Re: Replacing floor and transom in 1986 Sylvan 17' aluminum v-hull

I am currently in the process of replacing the floor in my 87 sylvan 17' fishing boat. I noticed the transom was also completely rotten and so I will be replacing that as well. For the floor I am going to tear out the old (keeping intact for template) and replace with MDO. Is 1/2" good enough or go 5/8" or 3/4"?

Should I use MDO for the transom and use 3 pieces of 3/4" to be 2.25" thick total? The motor is an outboard Mariner 80.

Also, for under the floor I would like to do foam blocks to make the ride smoother. I am on a serious budget here and I was thinking about using spray foam insulation. Rather than spray it directly into the hull I was thinking about making my own blocks by spraying it into a cardboard box and pulling them out when dry. Any other ideas on doing the foam blocks?

This is the first time I have messed with a boat and I cannot wait to get it done.

Thanks and any help is greatly appreciated!

The MDO plywood is really great stuff! If you're going to do your transom in 3/4 why not do your deck with 3/4 too, you may have some pieces leftover from your decking you can use on your transom and the 3/4 decking will be a stronger build. The 1/2" decks are supported by expanding foam beneath it, and without the foam the 1/2" decking is springy and bouncy.

Measure your transom cap and make your new transom the thickness needed to fit inside the cap, the old transom wood will swell and you can't get a good measurement of what it was originally.

The spray foam isn't that desireable for a couple of reasons:
1. It's more expensive than regular 2 part urethane expanding foam.
2. It has to be painted to make it waterproof (read the directions on the can).

The EPS sheet foam (rigid foam insulation) is the best bang for the buck if you're on a budget. The blue Dow, the pink Owens Corning, and the green Lowes are pretty much all the same.

If you still want to go with the expanding foam you can get a good price here:
http://www.uscomposites.com/foam.html