Smoothing out the RZ2's swim platform

[Booms]

Update

I have finally started my winter project. I took it to a couple of custom fiberglass guys around town and they wanted anywhere from $500 to $700 to fill in the bottom of the swim platform. After talking with on of the custom guys I have come up with a plan that will cost me ~$200 in materials. At least I think I have.

This is my plan...
I am starting out with 3/4" treated plywood. As you can see in Picture 1, 3/4" is a perfect fit. I traced the swim deck on top of the sheet and cut the board down to fit inside the supports (picture 2).
Once I have the plywood cut to size I am using adhesive to attach the wood to the swim deck. Let the adhesive dry for 2 days then I will coat the exposed wood with Interseal 670HS Surface Tolerant Epoxy. This paintable epoxy can be submerged in Saltwater with a coating thickness of only 10mils. So it should handle the bottom of a swim deck. Once I have all the exposed wood painted with a couple of coats, I am going to use an fiberglass/Epoxy Resin to fill in any gaps between the wood and the swim deck. Once this is done I will paint the entire bottom of deck with the 670HS. This will allow me to achieve a complete smooth water resistant bottom.

After starting this project I came up with some questions I would like to get everyone's thoughts on.
1. With 3/4" plywood in-between the supports I am now adding ~20lbs to the weight of the deck. Plus the resin and paint I would be easily adding ~40lbs to the deck. Is that too much weight?
2. Do I need all that wood? After reviewing Ragboys dialing it in thread should I just fill in the first 16 inches on each side of the deck and leave the middle empty? (Picture 3)
3. Or should I do what NICKYPOO suggested and only use wood that is 10" wide and cut it at an angle to allow the water to freely flow over.(Picture 4)

What are your thoughts?

[Wickedcummins]

use foam as a filler and glass over it

[NICKYPOO]

I would say do what NICKYPOO said. That dude is super smart.

I don't think the weight will be an issue. The transom is super thick and those platforms will easily hold three of four people. An extra 40lbs. is nothing.

I don't see why your second cut out diagram wouldn't work. There isn't that much of the platform dragging in the water at surf speeds. You just need the part that is dragging to be smooth.

[NHarp1]

The weight of plywood should be fine. I would suggest using foam fiber board (the stuff surf boards are made of) to fill in instead of plywood. That would take care of the plywood issue.
http://www.flyingfoam.com/FoamTypes.html
You could use the Blue board they put on the side of houses from Lowes. Same stuff!

[Timmy!]

Good idea Nick and Wickedcummins. You could wrap the foam in fiberglass and then bond it straight to the platform to test it out and see how you like it and then if it works solid, glass the whole thing in.

[NICKYPOO]

Agreed.

[yearroundboarder]

You can use foam core to fill in the platform or end-grain balsa. Both are commonly used as core in marine applications and bond well to fiberglass; plexus adhesive is a great product and would work well here. Not really necessary to use epoxy resin; polyester or vinylester are less expensive resins and more common. Either of these will bond better with the material Tige' initially used to build the swim platform.

[Nobody]

I don't understand this problem. Is the platform dragging into the wake? If it is, how is smoothing the bottom of the platform going to help, it will still be dragging but maybe not throw as much spray into the air. Is that the goal?

I don't know...this issue was brought up last year as well. I looked carefully at our platform and didn't see an issue. The bottom of our platform was raw fiberglass which left me puzzled as to why someone would do that. We sprayed it with black resin to seal it. I noticed our platform sits lower than one other RZ2 on Lake Tarpon, still I didn't see an issue. Maybe someone can shoot a video??

[majestic]

I'm interested to see how this turns out. I think the wave is still going to be disturbed by the corner of the platform unless you have a newer RZ platform that is narrower.

[Booms]

Update.
I am 90% done on modifying my 2010 RZ2 swim platform to remove the lip. I have one more coat of the epoxy to put on then I am done.

Materials List -
3/4" Plywood
Gorilla Glue
1 1/4" long SS Screws (Qty 12)
USC Duraglas Fiberglass Filled Filler (Quart)
Interseal 670HS (Gal) (Nasty Stuff)

After talking to many body shops/fiberglass guys I decided to go with Plywood instead of a Foam board - just from a rigidity/durability standpoint plywood is better.
1. I glued & Screwed and clamped the plywood down to the underside of the swim platform.
2. Once the wood was secured I used the Duraglas to fill any gaps between the plywood and the lip on the swim platform. I then got a earful from the wife for using that stuff in the house. The house stunk like it for 2 days. I had to show the MSDS sheet for her (She is also an engineer)
3. I then sanded the Duraglas smooth.
4. Taped the edges.
5. Then I use 670HS Surface tolerant epoxy. This I did in the garage. It is some nasty stuff. The 7 pages of the MSDS sheet had a list full of some nasty chemicals. What sold me on this stuff was that it dries as hard as concrete. The guy at the store showed me a piece that he had dry in a styrofoam cup. We hit it with a hammer and it did not crack or shatter. He even told me he had customers pour this stuff in the cracks of concrete 3 years ago and it is still holding up. He also thought it would handle the expansion/contractions extremely well. On the spec sheet for the 670HS it states "Provides excellent anti-corrosive protection in industrial, coastal structures, pulp and paper plants, bridges and offshore environments in both atmospheric exposure and immersion service." So I think it will withstand a few hours a week being submerged. I have probably shortened my life expectancy by a couple years by using it.
6. I mixed the paint with the activator the first time but I did not add enough to truly thin out the paint so the first application was a tad thick and not as smooth as I wanted it. I guess I could have added a thinner but I did not. Now that I have two of the three coats applied I think every coat I add smoothes it out a little bit more.

As soon as our temperatures get above 45 F in northern WI, which we are hoping it is before the 4th of July, I will get pictures of the wave.
The three photos show the platform after the 2nd coat of the paint. As you can see I cut out part of the plywood to reduce the weight. and I used tape to protect the screw holes for the brackets.

On to the next project fix all the cracks on the rales of the IS 4-Skim and Blue Lake.

[skippabcool]

Looking good.

[Wickedcummins]

wow you did it a really hard way. The foam would have just been a filler. Then used some glass mat and resing and done and would have keep it light and strong and water resistant as well. Tige hulls are made the same way

[Timmy!]

Looks good so far! Can't wait to see if it was worth it or not.

[Iwndr]

Nice Work Booms, let us know how it works, and you even are getting some extra ballast outta the deal

[NICKYPOO]

Knargly. Nice work Booms. I'm diggin' the bulletproof factor. I hope that works. Can't wait to see some pics. Do you have some "before" pics of what you are trying to fix with the wake?