bertram31.com

Figured I'd start a new thread on this. (I think the old one is very buried right now)

Scored some of the Captain Patrick recomended Groco external strainers (Brand new)at my local marine consignment store...good stroke of luck there as 90% of the time I go there sift through tons of junk and find nothing of any value. Must have been a lot of boats scrapped last year as the plcae was well stocked.

Anyway,weather is starting to warm up, and am getting ready to start putting things together...need just alittle more warmth to start epoxy work.

Have a few more questions for the faithful;

Bedding compund?
Have always used 3M 5200 underwater. Have had some folks I talked to trash talk it, and say I should use sikaflex 291. Any suggestions or expereinces on the best bedding compound?

Backing board?
Got a nice peice of marine plywood coated with 1708 cloth and epoxy from Bob Higgins.(Thanks Bob). While I was visiting him I saw that he used a lot of "penske board" (also called coosa board?) coated with 1708 and epoxy for various applications. That looked like it also might be a good material for a thru hull backing board...and looked impervious to water. Stick with the plywood, or go wit the high tech new material? Any thoughts?

Backing Board2?
I noticed a lot of folks are epoxying thier backing baords right to the hull rather than setting it in bedding compound. Anybody out there have any recomendations one way of the other? The thickened epoxy mount looks pretty substantial, so I am leaning in that direction.

Looking forward to getting going.....roughly 6 weeks until splash.

this post is like dealing with fire so i will be very explicit!!! i know there are many old timers out there who continiue to use plywood however times have changes and there are better methods . " yea but bob i totally encapulated in resin or expoxy" ok but what about the hole you put thru the center for the thru hole? did you take the whole damm thing apart after making hole and glass it then come back afterwards and coat it again?---bullshit ----down the road it will delaminate!! why not use something that is impervous to water intrusion to begin with. i use ipe` , the wood has been surmerged in the amazon for a thousand years .the plywood in my bertram bilge self destruck in 10 years or less put in by former owner and a pain the do over . you could use coosa board i love that stuff and use it for all my structual building now. sounds like i am quite opinionated those nonbelivers please look under you bertram air vents on gunnels and tell me what you see!!!

Bob...

You hit the nail square on the head! I have been rebuilding my '83 and had all the main cabin cabinetry removed so I could replace it all with teak veneer cabinets I built. While everything was removed I noticed the backing boards under the deck for the 4 engine room air scoops looked a little punky. When I touched them I found I could actually grab pieces of wood and pull them loose with my hands. Over the years rain water had leaked around the unsealed painted aluminum scoops and saturated the plywood backers on the underside of the deck, causing them to deteriorate.

I removed all of the original backers (double layers of 1/2"marine plywood) and replaced them with double layers of 3/4" PVC board material (Azek or equal), per Capt Pats article.. see http://bertram31.com/proj/tips/pvc.htm.

These backing boards will outlive most of us here!

Also, I originally had leaks around my main engine raw water intake through hulls, which were backed with 3/4" plywood, which had become soft and "punky" so I removed both and laminated some of the same PVC material to the hull, using GE 4200, and used these as backing boards. Solid and dry ever since.

I use GE 4200 for most things I bed to the hull.. so if there is ever a need to replace them I can break the seals and remove the 4200.. the 5200 product is so tough it is almost impossible to remove, so I don't use it much anymore. And I don't allow silicone caulking/sealant to get within 50 feet of the boat.. I hate the stuff!

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i used the sikaflex forget the # when i put my new rub rail on, i realy liked the stuff easy to work with, if the 291 is good for under the water i would go for it, stay away from the 5200 over kill, i take it your re bedding the raw water thru holes. the yards around me use somthing else and i cant think of the name, its a yellow tube with black lettering, aww could it be boat life

charlie you are right some yards use boat life.some use 5200 fast set in small tube because the yard men use a small amount and then leave gun and full size tube laying under the boat.what did walter say about the gene pool of the new generation? i guess i am to old to share any kind of passion or understanding for kids sitting around sniffing glue out of a bag!!!

And per Capt Pat, only hand tighten the thru hull until the 5200 has had time to set up and then tighten it down good so that it doesn't all squeeze out while liquid.

IRGUY i like the sound of "building teak cabinets" that is probaly the most relaxing building project i have done on my boat. incidently all the complexes belonging to oakdale yacth (about 80 acres ) there is not one tube of silicone anyware .that product does not belong on or near a boat that is a home product. all pvc products are not the same , for one stay away from box stores that is a imitation pvc just like all the rest of the crap in the store made in china and aimed at the uneducated buyer who is not familar with the real thing.thank god they don`t sell parachutes,life preservers,and bullets for my handgun!! azak is by far the best and a bonus when using azak molding on boat (like cockpit) the structual interity is thru and thru. easy to bent and solid. loves pl waterproof glue (green label) and can be used with heatgun for contour areas.

Bob/IRGuy-

You guys bed you backing boards in, or bond them with epoxy to the hull..or underdeck.

I 've seen some pix your bilge, but can't make out how the backing boards are set to the hull.

Captain Patrick-
I saw some very nice work on the boat you just did or are still doing?...same question, did you epoxy in the backing boards?

Giff,

For the Groco 1 1/2" full flow engine raw water valves, I used 1/2" Coosa board and epoxied them down. The valves are then bedded with 5200 & though bolted, the through hull fittings screwed in & bedded with 5200, and then the external filters added.

Giff...

The deck is very narrow on the B33 where the air scoops are, and the holes in the deck under the scoops are rectangular, matching the base of the scoop. Naturally the duct the air travels in is round, so I mounted one piece of 3/4" PVC under the deck with a rectangular hole in it.. this piece is bonded to the underside of the deck with 4200. I then made a transition piece by cutting an oval hole in a second piece of PVC, shaped so I could compress and squeeze the duct into it, then I held the duct to the transition piece with a couple of round head SS screws, with 4200 used to seal the two parts together. I then fastened the transition piece of PVC to the first with SS screws. This allowed me to (hopefully) minimize the amount of rain water that leaks around the assembly.

Thanks all, the feedback was much appreciated......These were the last pieces of data I needed to put my BOM together and order all my stuff.

SOLD on the synthetic product for backing board.....and the epoxy attach.

Giff

Giff...

Glad all the above input is useful!

I have been happy with the PVC wood substitute on applications where eliminating potential rot is more important than structural strength. I have experimented a bit with it using PVC pipe cement, epoxy, and 4200/5200 caulk/adhesive, plus some non-marine adhesives with PVC sheet and extruded "board" material. Except for PVC cement, which I suspect works by actually dissolving a small amount of the material on each piece and letting the two mating surfaces "recombind" into a single piece, I have found that epoxy and all the caulks I have played with need the smooth mating surfaces to have some "tooth" to allow the caulk to have a more open rough surface to adhere to. I use a coarse sandpaper (120 - 80 grit) to scuff each surface to be glued. I also us a pad sander and 180 - 220 grit paper to prep any surface that will be painted.

So far I have used PVC for my air duct backing boards, brackets and supports for things in the engine room and bilge, the upper guide track for the new teak sliding cabin door I made last fall, and am presently finishing (1st prime coats go on today) new window frames for the cabin aft bulkhead.

Also, another guy and I are starting to make and sell a line of rod holders and such things for the local pier fishermen, and use exclusively PVC and SS, so we can say our products are corrosion free.

I have to thank Capt Pat for his writeup on this material.. when I first read it I sort of poo-poo'd his suggestion, then I began to realize he was on to something and bought some of it to try. Now I realize that in it's place the stuff is very cost efficient. Thanks Capt Pat!

I have to thank Capt Pat for his writeup on this material.. when I first read it I sort of poo-poo'd his suggestion, then I began to realize he was on to something and bought some of it to try. Now I realize that in it's place the stuff is very cost efficient. Thanks Capt Pat!

Frank,

I originally posted that article back in 1996 on the old usamarine website... I actually copped onto the stuff as a potential use as a boat material in '91. The first use I had for it was to build new tackle center drawers on the 48' Ocean Yacht SS that I was running at the time.

My source, both then and still today, is Sunray Plastics in Riviera Beach, Fl. The owners found it somewhat interesting that I was using it as a replacement for plywood and on a boat. While they had a pretty substantial business from the local marine industry, they had not sold any PVC Foam Board to anyone in the boatbuilding industry. Only sign companies...

That same year I had the cockpit bolsters recovered. The original structural backing was of course 1/2" plywood, and while only a few years old, it was water logged and full of mold and early rot. I made new backing from PVCFB, used stainless T nuts, heating the nuts and melting them into place. Job turned out looking exactly like the originals. The owner of the canvass shop that did the re-cover was intrigued with the PVCFB & had never seen it before... Not much later I used the same technique for all of the exterior upholstery on a 37' Sea Ray. Then half a dozen or so individual jobs around 3 or 4 area marinas.

Within a few months the plastics shop was getting calls for PVCFB from other custom fabricators in the marine industry, then from some of the boatbuilders themselves, and several of the better canvass shops.

Today a large percentage of the PVCFB he does goes to the marine business. I can't be so vein as to think that I started an industry revolution, but I feel confident that I was one of the earliest marine industry users. The brand he supplies is Sintra.

PVC Foam Board as an Alternative to Plywood