Re-coring cockpit hatch project

shaker · Post by **shaker** » Mon Dec 20, 2010 11:39 am

Thought I would post some pictures of the cockpit hatches from our 35 Bertram. The coring is in need of replacemnt. The fiberglass and framing pieces are in fairly good shape. I thinking the framing must be made of teak althought it's hard to tell because they are painted in what looks like gray primer. I removed the framing that holds the sound insulation and centers the hatch over the hole in the cockpit. You can see from the pictures below that the coring is pretty rotted away. I can get some of it up with a putt knife. I'm thinking I will set the depth gauge on my skil saw and score the remaining coring to get it out. [IMG]http://i32.photobucket.com/albums/d41/i ... 4-Copy.jpg[/IMG] Framing is pretty fair shape. [IMG]http://i32.photobucket.com/albums/d41/i ... 6-Copy.jpg[/IMG] Where is that smell coming from???[:D] [IMG]http://i32.photobucket.com/albums/d41/i ... 6-Copy.jpg[/IMG] [IMG]http://i32.photobucket.com/albums/d41/i ... 4-Copy.jpg[/IMG] Top side looks in fair shape. [IMG]http://i32.photobucket.com/albums/d41/i ... 989033.jpg[/IMG]

mikehedb · Post by **mikehedb** » Mon Dec 20, 2010 4:38 pm

The wood is probably mohagany, which can look like teak.

shaker · Post by **shaker** » Tue Dec 21, 2010 1:05 am

Mike It could very well be mohagany. I googled mohagany and it has some of the anti rot properties like teak or port orford cedar. I hoping I can reuse most of those framing pieces. Teak,mohagany or cedar are not cheap. When I get some more done I will post a few more pictures.

photo finish · Post by **photo finish** » Tue Dec 21, 2010 5:44 am

Wow, Are all the 35s cored like that. When I pulled my cockpit floor it was still solid resin. There was only one or two small voids that I had a fiberglass guy fill.

Post by **dougl33** » Tue Dec 21, 2010 7:10 am

Someone must have re-done yours at some point. All the ones that I've seen (mine included) have had balsa coring that's glassed over.

shaker · Post by **shaker** » Tue Dec 21, 2010 3:12 pm

Pretty sure these are original hatches. The coring is covered by fiberglass which matches the fiberglass under the coring. It was cracked along the edges. I broke it away to show the coring which looks to be end cut balsa. I do think the rubber gasket was added to help seal the hatch at some point. However I could be wrong. The green arrow shows the balsa coring (rot) The blue arrow shows the mohagany framing (no rot just wet) The red arrow shows the fiberglass covering [IMG]http://i32.photobucket.com/albums/d41/i ... bigger.jpg[/IMG]

mikehedb · Post by **mikehedb** » Tue Dec 21, 2010 3:47 pm

I've seen a couple of Bertram decks and a lot of the balsa wood is like mush. Both boats they used a "bone saw" like a vibrating fein tool to cut the fiberglass on the underside of the deck, pulling it up in one peice if possible. They used marine plywood to recore the deck and glassed it all in. probably 60-70 lbs heavier than the original deck, but close to the same water logged balsa core. The new decks turned out very strong. I haven't done mine yet, but i will eventually. I have two small soft spots.

shaker · Post by **shaker** » Tue Dec 21, 2010 4:32 pm

Hmmmmm, Very cool Mike. I was wondering what I was going to use. I was thinking just an exterior grade plywoods then encapsulating the plywood with a glass in resin. I guess I should look into marine grade stuff. I will tell you that the hatches were heavy as hell because of the water in them. Luckily I haven't found soft spot in the cockpit floor.....yet!

Post by **dougl33** » Tue Dec 21, 2010 4:35 pm

Sorry. I meant that someone must have re-done Tim's.

DonW · Post by **DonW** » Wed Dec 22, 2010 2:37 am

I recently read something concerning the way some exterior grade plywood is waterproofed and how the coating prevents good long term adhesion of resin. First couple of years all is well and then here comes the water again. Hard to believe but if I was taking the time, as you are, then I would use marine grade. I actually flew up to MA and looked at your boat when Jim had it for sale. You got a hell of a great deal. Don

shaker · Post by **shaker** » Wed Dec 22, 2010 11:25 am

Hi Don, Are you the guy that bought the 36 Hatteras after looking at the Bertram? Opps! Sorry Don, I just saw your posting on the 35 bulkhead leak/sealing. Must have been someone else that looked at the boat. I feel very luck to have bought Jim's boat. When he dropped the price to 59k there was quite a few people interested in it. We just happen to be close enough to the Cape and kept in contact (bugging) with him during the whole time it was for sale. Yea I probably will do marine grade plywood. I will take a ride over to Kaliff's Lumber on Pope's Island in New Bedford and see what they have available. They supply lumber to the commercial fleet in N.B. Wonder if a water proof foam core could be use? Might not be rigid enough and probably more $$$. Wow...Just googled it! Divinycell 3/4" 48"x85" is $199. Might be worth it in the long run. Haven't measured it but I think one sheet would do it. Greenwood Plydeck XL is about $70 for a 4x8 sheet. Haven't had time to do much more to the hatches. The holidays and on and off snow showers have kept me busy. I hate winter more every year! Arrrrrgh BTW,,,,, It just started snowing again!!!

DonW · Post by **DonW** » Wed Dec 22, 2010 2:26 pm

Actually I probably am the guy. I had just looked at a Slane restored 36 Hatteras right before I looked at Jim's boat and it kind of skewed my expectations. By the time I figured out the deal was actually pretty good it was too late in the season to make a run all the way down to NC. Ended up with a 35 I found in Annapolis. Don

shaker · Post by **shaker** » Wed Dec 22, 2010 3:50 pm

Oh...OK now I got it. Congrats on your new 35 Bertram DonW.

JohnD · Post by **JohnD** » Thu Dec 23, 2010 4:31 pm

Shaker, go with a good mahagony ply Okoume or meranti here's a link with an explination and good prices (no 1st hand expierence though). http://plywood.boatbuildercentral.com/index.php epoxy bond to the fiberglass and wrap with fiberglass and you won't have to worry about it in your lifetime. you've got to consider that the original ply lasted 20+ years The fien multi-master is a the cats meow! I bought mine before the dremmel came out otherwise I might have went with that. I have an all aluminum cockpit insert, so I only have to worry about painting... After 10yrs and a gas => diesel repower, I've seen the good bad and ugly. I'm happy to help in any way I can. Shaker & Don, where are you guys at? I'm in Baltimore and am happy to share what little I know. br,

shaker · Post by **shaker** » Fri Dec 24, 2010 12:11 am

Hi John, Located on the south shore of MA. The Bertram's home port will be New Bedford MA. Probably would be a good idea to update my signature with that info. I like the idea of aluminum as a hatch cover. Probably could have something like that fabricated with a dog on each corner to make it water tight. I would imagine it would pretty expensive though. Those multi master tools look like they would make not only this job but a lot of jobs much easier. When I do replace the coring I think I might encapsulate wood first on both sides (fiberglass/resin). Then attach it to the aluminum frame with 4200 and the screws that go through the aluminum. I have to mess around with it to see if I can get the correct thickness etc. There isn't enough room for me to grind back the remaining fiberglass and over lap the new cloth without completely replacing the hatch.