bertram31.com

Guys,

I'm currently building a replacement composite rudder shelf out of PVC foam board per Capt. Patrick's instructions in the building tips section.

My cockpit deck has to be replaced next. I am considering either a painted deck similar to what Bob H did or a teak deck. Because it's nearly impossible to get Coosa Board here in Northern California easily (trust me, I've tried), I was going to create a composite deck with two sheets of Okoume. However, I am now wondering if a cockpit deck can be made out of composite PVC foam board.

1. Can a cockpit deck be made from composite PVC foam board?

2. If so, would I be better off with two sheets of 3/8" or three sheets of 1/4" to make the composite pieces?

Thanks in advance,

JohnV8r

John

Talk with a glass supplier. There are other options to Coosa. Penski board is one.

OK, I took Tony's advice and spoke to two local resin/glass suppliers, a boat builder I know in Southern California, and Diab (manufacterer of Divinycell). Interesting responses that I thought I would pass along.

The two local glass suppliers both said the reason why products like Coosa are not used more on the West Coast in boat building/repair is because the freight to get them here and minimum order requirements makes Coosa expensive and hard to keep in stock as they have to order in truckload quantities. That makes Coosa less attractive than other established options. That said, there is a shipment of Coosa BW 26 coming in on 2/9, so it's an option. For comparison purposes, pricing on Coosa vs Divinycell looks like this:

Coosa Bluewater 26 3/4" 4 x 8 sheet $229.64
Divinycell H80 3/4" 4 x 8 sheet $154.56

There is added cost for Divinycell as the boat builder told me he would use 1708 and 1.5 oz chopped strand mat on the deck side for stiffness and impact resistance and 1708 only on the bottom. Add in the vinyl ester resin cost and you're probably close enough on cost + time to make it a wash.

The boat builder said he likes Coosa Bluewater 26 for structural applications where adding structural rigidity is the primary concern. He uses Divinycell on decks and some structural applications because he finds it applicable on a wider range of projects. Divinycell allows him to control cost/add stiffness by choosing which resin/glass combination by application. When I described the bulkhead (aft of engines) that I also need to replace and explained I'm replacing plywood that is hard contact glassed in on the hull below the chines and tabbed on the hull sides, he said, "Use Divinycell. It will have more forgiving flex like plywood."

The Divinycell rep surprised me as well. When I told him I was leaning toward using two 3/8" sheets with 24 oz glass between the sheets, he told me a single sheet of 3/4" Divinycell was more than adequate stiffness for a cockpit deck on a Bertram 31. The boat builder confirmed this as well and said there was no advantage to make a composite piece out of two sheets of 3/8" versus using one sheet of 3/4" for a deck.

That's pretty much what I've learned up to this point.

John

Looks like it is all going to work out. Sometimes you have to do some hunting.

I used the Coosa 26 for the bulkhead behind the engines. I don't remember what I paid for a 4 x 12 sheet, but I thought it was up around 250 and that was in 2008.

John,
I used 1" PVC foam Core by Michigan Composites in 80lb density when I built my 3 piece decks and hatches, ( overkill on thickness but I wanted it to be bulletproof). I used 4 battens on the port and starboard pieces spaced evenly to reduce flex and spongy feel when walking on the deck , with 1708 and chop strand on the bottom with 1708 &1808 on the topside with white gel coat on the top. The top had sand finish that was applied with a Johnson & Johnson baby power container with medium grip sand sprinkled into the 2nd coat of wet gel. I used 2 layers of glass on the top for extra strength in case I dropped a bent butt 130 rod and reel or a heavy gaff onto the deck surface. The center section only had 2 battens (made of 1" foam core board. the fighting chair base plate and backing H frame supported the section over the fuel tank. The areas around the hatches were extensions 1" overlap about 3/8" thick of 1708 and chop strand for the hatches to sit on. I could move each section by myself without busting a nut when I needed to remove them for access to hoses and rudder tables below. The 4X 8 sheets cost me $150.00 apiece (materials at builders cost in 2000). I had the guys at the shop lay up each section and we had a 5'x10' glass top table for smooth lay up and we had chopper guns available. Not a huge project but I had all the correct material and tools. 30 years ago I made 3 sections of deck out of 3/4" marine plywood glassed over both sides lasted for 15 years before it started going south. They were heavy as hell and needed 2 people to take up the sections. I understand that you have a logistics problem getting the foam board in your area and shipping costs are high. Have you checked with any boat builders in the Southern Oregon area or maybe a RV maker in your area.
Pete Fallon

Hi Pete,

Thanks for the explanation. I am essentially going to do what you did. PVC Foam Core (Divinycell) is easy for me to get here. It is the Coosa Blue Water 26 that has been difficult to get. Coosa is a prefab fiberglass urethane based plywood replacement.

I really do appreciate you taking the time to give a detailed description of what you did as I will now incorporate the battens and the hatch lips...something I had not thought of doing out of Divinycell previously.

Thanks!

John

For whatever it's worth, I was told by some guys around here who had used coosa for decks that you needed to put a layer of glass over the top side anyway for impact and wear. It wasn't just cut it, fit it and paint it application.

John

http://www.cstsales.com/dealers.html

Take a look at these guys.
the link above takes you to there dealers list. Looks like you can mail order some stuff from them also.