Swim platform... looking for sugestions.
 

I have a project I am going to attempt, as I don’t want the expense of paying someone else to do it. I have a 32’ boat, that I want to build a 12’x36” swim platform for. With another 48”x18” step-up into the back of the boat.

For the main platform, my plan is build two platforms, each an exact mirror of the other, and then match them up as one platform.

The rough measurements per side are 36”x6’ and tapering to 30” or so on the outside. I will be building a mold for this.

My plan.. hopefully you can give me a couple pointers, and an idea if I am going overboard, or just right.. or need more.

Once the mold is made, 36”x6’, I will use a release agent (any suggestions?) Then I will spray Gelcoat. The real question comes now.....

How much gelcoat?

Then I was thinking of a layer of 18 or 24oz woven roving...
2 layers of 2.0 oz chopped mat..
¾” sheet of pressure treated plywood. (coated with resin)..
2 more layers of 2.0oz chopped mat...

How much resin should I need per layer? Each side?

The mold will have a lip of 3” around the sides and back. And 6” in the middle (to meet up with opposite side) and 6” where it will meet up with the transom. I plan on folding the fiberglass back over at the edges to double up the layers all the way around.

Hopefully this is enough information. Can you tell me if this is too much, or not enough. Weight isn’t that big of deal, where as overall strength is.

The 48”x18” will be built roughly the same, however I think I could leave a layer or two out.

Please let me know your ideas, and how much resin I should need, and approximate amount of fiberglass.

if you have any doubts about the stability of the parting surface in your mold use Part-All's high temp wax and PVA as a parting agent. It gives a slightly rough surface but the PVA acts as a barrier between the mold and your laminates/resin. You'll just have a bit of extra finish work at the end.

As far as the schedule this may better suite you needs

Gel in first
layer of 1.5 oz chop strand mat
two layers of 1808 (or 1708)
3/4" scored foam core
Two more layers of 1808 (or 1708)

mat goes in first to control print through and if you were using roving you should use it in between all layersof that as well. Much easier and stronger to use a nice bi-ax laminate and no need for the mat in between, 17 or 1808 will be fine. uscomposites.com is a good supplier for everything your gonna need except the core. You may also have to add in a few ribs to stabilize the whole thing.

You wont be able to fold fiberglass over at the edge for added strength it will be better to just cut a few extra strips and beef it up that way. I will try and come up with a shopping list later after a total build process is established.

Cool.... Thanks a ton...

I can find everything except the foam. is that somethign I can buy at a local store, or what it is called? What should I use for ribbing?

Overall, how much resin should I be needing?

Thanks

I would get a five of Vinylester and jamestown has foam in scored and flat sheets. The ribs can also be done with the foam as well.

http://www.jamestowndistributors.com...80+Grid+Scored

You have been a ton of help.

Ok.. I think I have my list... I choose the 50" material so I can cut the strips off to double up the edges.

1.5oz choped strand. 50"x5yrds

Biaxial Mat 1708 50"x25yrds

I looked at the 435 Standard Polyester Resin on US composites..
5 gals. (is vinylester that much better?)

I am guessing probally 1.5 gallons of gelcoat for this project? Probally gonna get 10 gallons ( I plan on regelling the bottom of the boat.)

1 gallon PartAll spray / 1 14oz can of Partall paste.

Let me know if I missed anything....

I looked at the foam core you posted (gonna look and see if I can find that local) also...... Curiuos could i make my own board using the Urathane foam UScomposite has? if so, what density should I get? 8lb.. 16lb?

BTW... I super appreciate all the insite.
Thanks
Skip.

435 is a great resin and will work fine, vinylester is stronger and has a bit more work time when mixed properly.

A gallon and a half of gel should get you through this project no prob, my guess is you will use just less then a gallon. Unless you are doing the bottom of the boat very soon i wouldnt get the extra, shelf life for gell is about three to six months or so.

The foam core really isnt available at anything like a local hardware source. These are high density poly foams designed for this use. You might be able to find something similar at industrial insulation suppliers but the costs are about the same, I have a friend in that biz and we looked into it. You could still use plywood, its been done for years but they have a limited life span. Using vinylester could extend that as long as you take great care in laminating to ensure no voids. Mix and pour foams are not suitable as the expand and you will not be able to keep it level.

Ok... I think I got it all.

I found the foam from a distributor that is local enough that I can pick it up, and save on the shipping.

http://www.generalplastics.com/produ...il.php?pid=21&


I am gonna go with the 15lb density 3/4" TR-marine foam. With the schedule of resin and mats as stated previously.

Ok you said I will need to put ribs in the foam prior to fiberglassing.

how big of ribs, and at what interval? 3/4"x 3/4" x 48" (roughly the full length of each side) ? at 3", 21" 38"... that leaves 2" or so of clearance from each edge.. and use these ribs as mounting supports for the brackets I will be building, and the swim ladder.

nice stuff, that will work good. After you have the piece cut and final fit you will want to round over any edges that the glass will have to bend over, make a pretty good radius of 1/2 inch minimum. The ribs arent cut into the foam but rather added on top, kind of like bulkheads or stringers. Cut some long boards out of the foam about 3 inches wide and use them like a T joint. After you get the main platform done, your basically just trying to "joist" it from the bottom and tie it in with the sides (hope that makes sense) you dont need a whole lot of them maybe two full width ones space evenly. You could also run them front to back if it helps with mounting and attaching the ladder, either or will work.