[Motoxxx43]

I am in the process of replacing 3 seats out of my SC21. I have been told of a number of options for replacing the plywood part of the seat. Some say use plywood again and coat it with a water treatment. Some say use marine plywood. And last but not least I have found the product I want to use- King starboard. This is a plastic which means it will not rot or get weak if it gets wet. I have managed to find it for reasonable prices and looks like it will run around 160$ for all three seats. The only problem I have is there is not a store nearby that has any product I can look over. I dont know if I should be getting the 1/2" or the 3/4" for seats that are 19x25. I see the 3/4 as being the safe route but at the same time it might be overkill and also end up costing 50$ more.
If you have worked with this stuff and know from experience what thickness I should use Im up for advice.

Here is a link to the product if you are not familiar with it.
Marine/RV | King Plastic Corporation

[ColoradoDiablo]

I used it in my boat for the seats in the bow , the back , and the sundeck , and am using the starboard AS(antiskid) for the fuel sending access hatch. I am also in the process of making a console from it.
I think it's the best thing since sliced bread. No matter what you do to wood , sooner or later it goes to crap. Not King Starboard.
It is just as easy to work with as wood except it doesn't glue well. I bought a hot air welder to do my console so well see how that works.
I recommend it highly!

1/2" is plenty for that size of cushion.

Here is a pic of one of my side rails I did in starboard:

Larry

[Motoxxx43]

Good to know. I'll be ordering the 1/2'' then. As for your photo, it did not load or it is not visible. Thanks for the reply!

[ColoradoDiablo]

Problem got to be on your end Moto. Photo shows up . Maybe it hadn't loaded yet?

Larry

[Motoxxx43]

Eh, worked this time! Looks good. Im going to order some 1/2" soon. Thanks for input

[Motoxxx43]

I got my seats back yesterday from the upholstery shop. They look great. The kingsboard was easy for the shop to work with too. He said it stapled just like wood. I know for a fact it cuts like wood. I had the pieces cut to my specs and then shipped. Well, 1 was too long and the other 2 were too wide. I ran to Lowe's and they cut them. The saw does not melt the plastic while cutting and the edges were sanded just as easy as wood. The 1/2" thick seats span 19"x25" and are only supported on the edges. The seats hardly flex and will be plenty durable in the SC21.

I ordered through "scrapplastic" on Ebay. It was the best price by far but like I said they did not cut exactly to my dimensions.

[Oregondunes]

ive used Euro Ply before too. better then std plywood, not as spendy as marine ply

[ShabahZ280]

Originally Posted by Motoxxx43

I ordered through "scrapplastic" on Ebay. It was the best price by far ...

I've ordered from them too, great prices!

[Chickman]

Larry, I'm thinking of replacing the wood on my sundeck w/ 3/4 inch starboard. What thickness did you use and did you have any issues? Thanks in advance.

[Motoxxx43]

Hey Chickman, what boat is this on? On the original Mariahs there is quite a bit of support for the sundeck meaning the entire weight is not just supported on the outside edges BUT in the middle as well. I would think the 3/4 in is good but Im sure the 1'' would not hurt! Another suggestion I would have- use the starlite board. It is just as strong as original kingsboard and weighs a lot less. Since the substrate is covered by upholstery the perforated edges of the starlight will not be visible. The 1/2'' stuff I used is much heavier than the 3/4'' wood it replaced- yet stronger.