20 bertram bahia mar

CaptMarkB · Post by **CaptMarkB** » Aug 13th, '08, 15:00

Recently aquired a 1969 20 bahia mar for restoration. The gelcoat is badly checked, and I'm told it needs to be taken down to glass for refinishing. Anyone with experience or advice would be appreciated. Deck will be removed, stringers and transom replaced, etc. Also looking for factory brochure(s).

CaptPatrick · Post by **CaptPatrick** » Aug 13th, '08, 15:54

Mark,

You've been told right... Any attempt to cover up the checking, other than to sand it down will only come back to haunt you.

The good news is that gelcoat sands down fairly easily. A DA & 80 grit paper will do most of the work. Some tight detail may have to be done by hand.

The bad news is that while not all of the gelcoat may not be checked, all of the gelcoat must be drastically reduced in thickness, if not entirely removed.

Gelcoat age cracks once continued shrinkage reaches a point that the surface tension is too great for the gelcoat to hold up. At that point a crack develops relieving the tension. Much the same way mud sun dries & leaves cracks.

Un-cracked gelcoat, by being sanded very thin, will usually not continue to crack under primer & paint, but it needs to be sanded to the point that you can almost read the glass through it.

The bridge in the B31 that I'm currently working on had been excessively gelcoated & resulted in a high degree of age cracking. The hull and cap weren't as bad, but the whole boat had to be heavily sanded.

After you've finished sanding, prime with 2 coats of Awlgrip 545 epoxy primer, fair if necessary with Awlfair, (also an epoxy), and re-prime with 545 or High Build primer as necessary.

Br,

Patrick

CaptMarkB · Post by **CaptMarkB** » Aug 14th, '08, 08:59

Thanks for the advice. I figure the boat to be a two to three year project. I'm also repowering, the boat is totally stripped of any hardware right now and all old drive components were discarded. Has anyone had any experience with Volvo or Cummins diesel I/O repowers with this size? Any input would be appreciated.

In Memory Walter K · Post by **In Memory Walter K** » Aug 14th, '08, 09:37

I was very impressed with the Volvo D-3 combined with their Ocean series graphite Duoprop unit. Nice fit in the engine compartment. All the diesel combos are expensive, but operational performance and fuel consumption are outstanding. Walter

CaptMarkB · Post by **CaptMarkB** » Aug 19th, '08, 08:36

I think that was the repower that "Shipshape TV" did on thier 20 moppie. If I remember, the numbers were awsome. Was that the 190HP version? Still looking for any literature/brochures on my vintage 20. Thanks for all the input.

Peter · Post by **Peter** » Aug 19th, '08, 09:54

Put a little over 200 HP gasser in it and it will be a sweet little serious blue-water sport boat that flies. Under that HP it is still a nice ride, but not as sporty.

We have had one in the family since the 1960's and just love that boat! Beach picnic, water ski, fish, wake baord whatever...sometimes its fun just to go catch some air off the top of big swells.

Lots more info and advice on the 20's over here too:

http://simplifying.net/phpbb/index.php

Peter

Craig Mac · Post by **Craig Mac** » Aug 20th, '08, 14:41

Capt Pat,

What's the deal with your current project? Is this a full restoration?

Any special features?

CaptPatrick · Post by **CaptPatrick** » Aug 20th, '08, 15:23

Craig,

Total restoration & customization. Similar to "Buddy Boy" Working by myself, so taking longer... Hope to be ready for paint by March. Haven't had much time to devote to building web pages. Still in the uggly duckling stage...Quack, Quack

Br.

Patrick

Harv · Post by **Harv** » Aug 20th, '08, 18:13

CaptMarkB wrote:Thanks for the advice. I figure the boat to be a two to three year project. I'm also repowering, the boat is totally stripped of any hardware right now and all old drive components were discarded. Has anyone had any experience with Volvo or Cummins diesel I/O repowers with this size? Any input would be appreciated.

Last month at the Mid Atlantic Rendezvous, I had the opportunity to take a ride on a restored B20 Moppie, that was powered with the new Yanmar 220hp 6cylinder diesel with a Bravo III duoprop. Impressive is an understatement. Ask John F. or Doug Crowther,......they were on for the same ride.

John F. · Post by **John F.** » Aug 20th, '08, 21:22

Harv's right....very impressive, and the fuel numbers were great. Only problem I saw was that the boat at idle was moving along pretty well--forget slow trolling for stripers.

CaptMarkB · Post by **CaptMarkB** » Aug 21st, '08, 09:33

Once again, I'm so happy I found this site and the pool of knowlege that comes along with it. Just on a side bar, how does the waterline of the 20 look with the volvo 6 in it. I haven't had an opportunity to inspect one in the water at rest. It appears that the waterline is at the top of the return of the reverse chine and the boot stripe above that. Any suggestions? I know I'm getting ahead of myself but I just think this is such a cool little boat. Thanks again. P.S. any problems with keeping the original glass tank if I go diesel (after I thoroughly clean it)?

Mark

ianupton · Post by **ianupton** » Aug 21st, '08, 17:42

Mark,

I have alot of B20 literatur in PDF format that I can email you.

I have been in many a B20. My old B20 Bahia had the original straight six and the water just kissed the chine (stern) at rest.

The guy who purchased my hull did a complete resto and put in a 5.7 volvo with duoprop. (very fast... high 50's)

I think the best power for this boat is the 4.3 V6. A fuel injected V6 with duoprop of Bravo III will do low to mid 50's. Plenty fast for the hull.

Weight wise the 4.3 is heavier, but you can compensate if you are completely redoing the boat. My recommendation would be to move the fuel tank forward to the cabin bulkhead, place batteries forward and you should not squat much more that with the original engine. If you do squat, you can do wonders with the chine stripe to virtually make the 'squatting' dissapear.

If $$ were no option, I would go with the volvo D3 and composite drive, but I think the payback would be far too long. The V6 is fast, easy and more fuel efficient than the original engine.

Ian.

Kevin · Post by **Kevin** » Aug 21st, '08, 17:56

Steyr 230 or 250 HP. Straight six, light weight (lighter than small block gas), great on fuel. Look into them, expensive but worth it in my opinion.

scot · Post by **scot** » Aug 23rd, '08, 14:43

Still in the uggly duckling stage...Quack, Quack

Thanks Capt, now at least I know where I am, and there's a name for it.

CaptMarkB · Post by **CaptMarkB** » Aug 26th, '08, 17:37

Hey, if "ianupton" can send me the pdf literature on b20's via the message link, that would be great. I tried emailing, don't know if you got the message. Great feedback on power options, has anyone had any experience with cummins mercruiser bravo 3 diesels? The reason I ask is I have a local guy who does sales and service, WESCO marine in Hampton Bays, New York (your town Brewster, say hello to the Jackson boys!). Still looking for factory brochures on b20's.
Mark

CaptMarkB · Post by **CaptMarkB** » Aug 28th, '08, 15:10

Capt. Patrick, good advise on the gelcoat repairs. Another question; on the badly checked area's of the cockpit sole, there are small black lines which mirror the checks which were sanded off. I was told by a good local fiberglass guy that I should put a layer of mat over the bare glass and fair that to prevent the checking from re-appearing after paint. What's your or anyone else's opinion? I plan on keeping the boat and want to do it right. Don't mind the sweat equity. Mark

Carl · Post by **Carl** » Aug 28th, '08, 16:34

Kevin wrote:Steyr 230 or 250 HP. Straight six, light weight (lighter than small block gas), great on fuel. Look into them, expensive but worth it in my opinion.

I will second the Steyr's. You have a good dealer in your neck of the woods as well.

Carl

CaptPatrick · Post by **CaptPatrick** » Aug 28th, '08, 17:24

CaptMarkB wrote:...there are small black lines which mirror the checks which were sanded off. I was told by a good local fiberglass guy that I should put a layer of mat over the bare glass and fair that to prevent the checking from re-appearing after paint. What's your or anyone else's opinion? I plan on keeping the boat and want to do it right. Don't mind the sweat equity.

Odds are those lines won't ghost back, but if any of them look particularly bad, then glassing over them isn't a bad idea. Rather than mat, I'd use a couple of layers of veil. Easier to fair back...

CaptMarkB · Post by **CaptMarkB** » Sep 1st, '08, 09:45

Anything to make fairing easier sounds good to me.

CaptMarkB · Post by **CaptMarkB** » Sep 12th, '08, 10:53

anyone had any experience sandblasting gelcoat off, or any other media?

CaptMarkB · Post by **CaptMarkB** » Sep 29th, '08, 20:58

Capt Pat, I was reading an earlier post talking about awlfair epoxy after sanding. Am I correct in that all polyester/glass repairs should be made prior to epoxy and then paint?

CaptPatrick · Post by **CaptPatrick** » Sep 29th, '08, 21:28

Mark,

Correct. Polyester resin won't bond to epoxy. For best adhesion of the Awlfair, give the raw work a coat of 545 epoxy primer, then fair away with the Awlfair, (also an epoxy).

The Awlfair can be applied over the 545 as soon as the primer has hardened enought to touch. If you can drag your finger lightly over the primer and not feel a drag, but a direct single point touch feels tacky, it's ready for Awlfair without sanding. After 12 hours the 545 will need to be lightly sanded.

Br,

Patrick

bertram31.com