Building a swim platform

[erikgreen]

Re: Building a swim platform

There are a couple different ways to build stiffness.

The overall way is thickness... make the platform thicker. But making it thick enough just using plywood covered with glass will make it very heavy.

A better way would be to use the downturned edge you see on a lot of platforms.. it reinforces by stiffening the perimeter of the platform.

Or, use a single thickness of ply for the main core and stiffen it with 1 inch strips of ply laid on edge across the bottom of the platform full width. Glue them in place and glass over them.

You can buy stainless steel swim platform supports from greatlakesskipper and other sites, by the way. Nicer looking than the aluminum or other tubing.

An excellent source for building techniques is this thread on ClassicSeacraft.com:

http://www.classicseacraft.com/foru...r=41537&page=0&view=collapsed&sb=5&o=&fpart=1

A guy by the name of Chuck Strick rebuilds his seacraft completely, including custom scratch-built hatch covers and gutters, fiberglass panels, a bracket for his outboards, and seat boxes.

The techniques he uses for hatches would adapt readily to your swim platform... essentially, take the time to fit a bunch of 6 inch 1/2" plywood squares in a grid for the core instead of one piece of ply, and glue them in place with cabosil thickened resin, and it'll be super stiff and strong. Very much worth reading for all the techniques covered.

I'm about to build a swim platform for a 46 foot roamer ("about" meaning in the next two months or so) and I'll document that. I'm planning on using a flat tabletop with 1x2 raised edges for a mold, and doing a wood core layup with 8 inch squares of 3/4" exterior grade ply. Probably I'll use about 4 layers of mat and 6 layers of 1708 with poly resin to do this. Gelcoat sprayed on first will get me a nice finish. Supports will be the ones on the boat already, aluminum tubing. Anti-skid optional, possibly bedliner or teak strips.

Erik

 

[Greg Mrozinski]

Re: Building a swim platform

Good info. Sounds good.

 

[CascoBay]

Re: Building a swim platform

Thanks to all for the input, I will be doing some more reading!

Here is a sketch I made today (not to scale on some items):

I also plan on using some 1.5" x 1.5" pieces for beams running the width of the platform that are not shown. I really think that using these in combination with the 3/4" ply, all fiberglassed together will make a nice solid piece.

 

[Greg Mrozinski]

Re: Building a swim platform

Sounds good. Go for it and keep us posted on your progress.

 

[CascoBay]

Re: Building a swim platform

What is the best way to transfer the curve of the transom to the plywood? Trial and error for the most part or is there a science?

 

[sasto]

Re: Building a swim platform

if sh were mine I would cut out a template using cardboard.

 

[CascoBay]

Re: Building a swim platform

I thought about that, but wondered if there was another way- thats one large piece of cardboard.

 

[drewpster]

Re: Building a swim platform

For templating I prefer tempered hardboard (peg board without the holes) it's cheap and stiff enough to hold its shape very well once cut. You can use a jig saw with a fine tooth blade to cut it. And its available at Blowes or Home Depot.
You can make a divider out of the hardboard as well for marking the shape of the transom. Then you can refine the cut and fit it the way you want with the hardboard before transferring it to the ply.
If the curve of the transom is very slight, you can use a cheap set of dividers from the kid's school supplies rack. If not, you can make a set using a couple of strips of wood and a bolt for the hinged end of the divider. Drill a hole in one of the strips to hold a pencil at the marking end of the divider.
Set the flat edge of the template board against the transom. Adjust the dividers to the widest gap between the transom and the edge of the template. While holding the pointer end of the divider against the transom, and the marking end (pencil) on the template, walk the divider down the transom. This will transfer the shape of the transom to the template.
Cut the template out and refine the shape using a saw or a sander and fit it to the transom. wallah! template done. :redface:

i hope this made a little sense,

enjoy
drewp

 

[Greg Mrozinski]

Re: Building a swim platform

Drew's got it.

 

[sasto]

Re: Building a swim platform

i hope this made a little sense,

enjoy
drewp

Makes good sence to me, drew..Your way is much easier for the beginner and will make a better pattern for him. We have even used stir sticks hot glued together for a template, but I can't recommend that either.

We have made a compass like you are speaking about with the stir sticks bolted together and the pencil simply taped to one end. Obvioulsy we has a shop full of stir sticks.

 

[ingalp01]

Re: Building a swim platform

In reference to the non-skid surface, I used grip tape on my platform when I re-finished it.

Grip tape, ie. the same stuff used on skateboard decks. I bought it in a roll from the local skateshop, or you can buy it on e-Bay cheap.

Cut it in to two inch strips and then place the strips two inches apart on the swim platform. Looks good, works great, should last about 5 years, and the re-do for about 20 bucks.

My .02 worth...

 

[Yacht Dr.]

Re: Building a swim platform

I think it would be easier to make a mold.

I would lay out your transom template ( however you want to do this ) and transcribe that on a flat piece of waxed up doorskin or formica.

Basically put a 4x8 piece of formica on flat ground.

glue or shape 6" of stripped formica to make the form of your likeing for your platform.

finger in some clay for your radiuses/edges.

wax it up good.. then brush/roll or spray gel. .. when the gel is almost cured then start laying up your CSM 2x then possible of 2 1708s

Let that cure.. put some 2x or ply supports in the mold .. layup some mat over these.

Pull the part off the mold and trim as needed.

You can make a factory looking part with this ( flanges and everything ).

No matter what you do your going to glass it.. to me Id rather make a simple mold then have to glass your ply and put an 8" pad grinder ( lots of glass dust flying all over you ) on it to Flatten it out.

Just me though..

YD.

 

[sasto]

Re: Building a swim platform

YD's is the way I've made many parts..... and going to fabricate a swimplatform for the lady using the same formica. Simple and lightweight is the way I like to go. Im putting the non-skid pattern in the mold and an outline of a sailfish.

 

[CascoBay]

Re: Building a swim platform

Thanks to all for the input.

I am finishing up winterizing of the boat and other projects and will begin the swim platform shortly. I will post many photos.

I am hesitant to use a mold to make this as I have never done that before. I have built a couple boats- but always used plywood as a core and fiberglassed around it.

So far I plan to just use plywood and so forth and then glass over it all, unless theres a really good reason to do otherwise.

I guess I dislike change!

 

[Yacht Dr.]

Re: Building a swim platform

I think it would be easier to make a mold.

I would lay out your transom template ( however you want to do this ) and transcribe that on a flat piece of waxed up doorskin or formica.

Basically put a 4x8 piece of formica on flat ground.

glue or shape 6" of stripped formica to make the form of your likeing for your platform.

finger in some clay for your radiuses/edges.

wax it up good.. then brush/roll or spray gel. .. when the gel is almost cured then start laying up your CSM 2x then possible of 2 1708s

Let that cure.. put some 2x or ply supports in the mold .. layup some mat over these.

Pull the part off the mold and trim as needed.

You can make a factory looking part with this ( flanges and everything ).

No matter what you do your going to glass it.. to me Id rather make a simple mold then have to glass your ply and put an 8" pad grinder ( lots of glass dust flying all over you ) on it to Flatten it out.

Just me though..

YD.

Hint Hint.. Im trying to suggest a Trade Secret here

Your making a Plug... I suggest making a throw away Cheap Mold out of door skin and Clay and make a PART ... think about it...

YD.

PS. Wow..Its been along time since Ive seen a "Pram" .. squirely little buggers hehe .

 

[CascoBay]

Re: Building a swim platform

I understand, its just that I have never done it so I fear my success ratio would be low.

 

[lime4x4]

Re: Building a swim platform

This is how i did mine using 1/4 thick ss flat bar steele and trek deck boards.

 

[jonesg]

Re: Building a swim platform

Yotdoc is correct, a layup table and form the perimeter of the part with strip wood or plastic, induce curved edge with clay.
See the classicseacraft suggested by Eric, Strick made lots of parts that way.

Heres a slideshow, the guy rebuilt everything and shows some great ideas of what you can do, a platform is very basic and a good DIY to learn the process.
http://s728.photobucket.com/albums/ww290/88bowtie/?albumview=slideshow

 

[CascoBay]

Re: Building a swim platform

Okay lets say I did it with a mold, what is the layup required? What type of mat/cloth, ect? Any core at all involved? Perhaps where the supports are mounted?

 

[Yacht Dr.]

Re: Building a swim platform

I would use Door skin or Formica for the mold..the clay for the corners to make radi. Wax it.

Apply coatings of unwaxed gel. Just at the moment were you can brush without dragging the gel around start your glass (spray would be better but...).

You could use all mat if you wish. If in doubt then start with 2 layers of 1.5 oz mat lapping up on your sides. You can then lam a layer of 1708 ( or woven roving ) then mat. slap a piece of 1/2" - 5/8" ply and 2 more layers of mat to finish.

After that has cured enough you can start putting in your 2x(whatevers needed) or 3/4 ply for support. Mat a few layers over those and your done. You can Finish with gel if you like.

Pop it and little sanding and buffing where your clay was..

For your nonskid you can use Fleximold or apply griptex afterwards.

Like I said though..you can do this all out of mat..just build till its strong enough for your needs.

YD.