bertram31.com

Pretty mean, huh....who'd a thought?

Nic

first pick should be the old bastard. launching a f-18 had better be left to the pro`s you are disputing the fact that basa core lay up is crap with the master.would you like to see why my neck has bone spurs coming out of it from a basa core lay up coming apart at 85mph .perhaps you launch the f-18 and i built the boats.(i`m surprise at you)

You got to keep up, here is some good reading.
http://www.diabgroup.com/europe/literat ... /H_man.pdf

dammit

Divinycell hull huh? It sure makes really nice flybridge panels, hatches, bulkheads, etc. but in a hull?
Yeah, the core is gonna make that hull stiffer.. but over time it's gonna flex, like a friggin female bodybuilder...kinda brings Randall's 'oreo cookie' scenario back to mind.
Anyone familiar with the Benchmark power catamarans?

36 & 38' sportfishers, not made anymore, cored hulls... Forgot the material...My good buddy has been redoing a storm (04) damaged 38' for a few years now up in Indian Town. I bet Pete's seen her up there. I'm not a big cat fan, but I really like these hulls. Apperently Calcutta cats picked up the molds, for their new 360cat.

My experience with balsacore:

To be fair, thats a '64 B25 exp.cruiser (same boat that Luis was wondering on) with 40+ years of God knows what goin on on that bow... removed it with a flat shovel. I'd say it's weight was 99% water, 1% water satured balsa...uffda! Not fun. I'd imagine it'd be fine, if it were never, ever exposed to moisture.

Oh yeah, HotheadRobbie. Thought of you today. I was down in the bilge of a 37' today prepping her for some bilgekote... Was previously done with awlgrip, chipping down low in the keel, ok elsewhere. One particular chip, I pulled on it, and a honest 40" x 8" section of awlgrip peeled right off, like a trophy banana... I got to thinkin about how you said you've never seen anything more than tiny blisters, while I've commonly seen massive peeling... And while I can't account for everyone's prep & proceedure, I can for vouch for several...so,
I began to think of it in the difference in lattitude.
Boats down here are in the salt year round, whilst up there, not sooo much.
Higher temps, ambient humidity, and rainfall amounts as well...
A bit more at work here than the "awlgrip will only fail in a bilge because of insufficient prep" that you tossed out there.

Looks like the Capt. is $20 richer. Cough it up Sean.

Tony Meola wrote:Looks like the Capt. is $20 richer. Cough it up Sean.

Yes of course - I'm an honorable gambler. Jeez who are you his bill collector? :)

I think I'll put a $20 check inside a layer of Divinycell cut to the size of an envelope, then glass the thing shut on all sides, and mail it. If he can open the fiberglass oreo and get the check out without a grinder, then when the check clears I'll know he was right
(knew that was the case anyway)

DIAB is the largest structural foam core manufacturer, with production facilities in Sweden, Italy and the U.S. It produces Divinycell and Klegecell, both semi-rigid, crosslinked PVC foams. Both are used extensively in the marine, transportation, wind and general industrial products markets, says Gutierrez. The company also produces a linear PVC foam, Divinycell HD, used mainly in military applications.

The toughened, high-density Divinycell HD was recently selected as the core material below the waterline for the Visby-class military corvette ship, built by Swedish marine fabricator Kockums for the Swedish Royal Navy. The 300-ft long minehunter/anti-submarine vessel is constructed entirely of resin-infused carbon fiber/vinyl ester cored composite panels for extreme light weight and stealth characteristics. Kockums' composites designers selected the Divinycell PVC product for its high elongation and impact resistance, to counteract the high-speed ship's slam loads encountered in rough seas as well as the forces of underwater mine explosions.

I dont really know why you call me hothead? Can we not discuss things here?

I am a huge fan of gelcoat in the bilge, for some reason people like to use paint. I would never use ANY paint in a constantly submerged area- I always advocate gelcoat. I did not think I had to explain in detail how to prep a bilge if someone wants to use paint, we were discussing more then teaching or lecturing, I was not putting up a "how to" article. Who is to say how that bilge was prepped that the sheet of awlgrip can peeling off like a banana?

And on a final note- I do not use or like Awlgrip, I use Imron. In bilges I use imron 333 aka 3.5HG. I actually refuse to even awlgrip a hull thats how strongly I feel about it.

I have recored a ton of boats, and they all fail from poorly bedded hardware, it will not magically start failing for any other reason, you have to introduce the moisture. It can be as simple as anchor chocks on the deck and give it 10 years and the whole deck will be rotted.

Bob- And I will still stand behind my balsa comments. I may not have launched jets but I have been around the block too, this aint my first day at the rodeo either. You of all people should know speedboats use balsa, they flip and stuff and dont all self destruct. Who is to say what would have happen to you in a different layup boat? Sorry I do not agree with the "master" and that upsets you.

I apparantly did not understand this board when I joined, I thought this was a hands on board where ideas were traded.

Capt. Bob,
How disappointing. You should never have posted a picture. I had no idea from your posts that you were nearly my age. Whew!
For years I listened to Paul Harvey on the radio and in my mind's eye I saw a Walter Winchell type hunched over a 1940's microphone, hat set on the back of his head with a Press Pass stuck in the band and he was giving us the scoop. Well several years ago I was speaking at a conference and he was key noting. I met him and my image was blown forever. He about 9'4", gangly, slightly goofy looking, red haired. Another image blown. It took me years to get over the visual. Still love to listen but Winchell is gone.

Simmah down now...
Of course it's a hands on board where ideas are tossed around. I've just noticed that you tend to get a little hot under the collar when someone disagrees with something you've typed...
For instance, leaving the comment

btw- I hate formica!

right after Patrick posted up a pic of his slick divinycell/mica creation is not an idea whatsoever... It's just slingin' shit around...
And I simply called you on you're statement of paint failure in a bilge... I thought it was strange to say that a product applied in an area that the manufacturer does not recommend would only fail because of incompetent prep work... Come now. I used to work for a few paint manufacturers, and beleive you-me, they want to be able to list a unending variety of uses for their products...obviously equals more sales. So, if they specifically state it shouldn't be used in a certain situation, there is a good reason behind it. Usually years of real world testing, on varied substrates, in varying conditions.
I'm not gonna claim to be familiar with the Imron you're using, I'm sure it's a great product like the rest of the Imron lineup, and very well may be suited for use in a bilge, I dunno...
Speaking of ideas, you never gave out any info on the "acrylic" you use for the cockpit panels... what is it?

now i know why my painted bilge works so well....there isnt any water in it. shaft seals and a shop vac.

The new improved H Grade is intended to be used for the vast majority of composite applications where both hand laminating and closed molding processes such as infusion are employed.


With the new H Grade, major improvements in all significant performance areas have been achieved. Strength properties have been increased by an average of 10% whereas the shear properties (normally the most important property for a sandwich core material) have seen even higher gains. Shear strength has been increased by up to 20% and elongation to break has risen by up to 50%. The ductility of Divinycell H has also been markedly improved making it ideal for applications subject to fatigue, slamming or impact loads. Where a more brittle core material might well shatter or delaminate as a result of an impact, the ductile performance of the upgraded H grade allows it to absorb energy when deflected without structural failure.

Does Capt Patrick get 20$ each time?

The bottom line on the cores is that time will tell. Until today the results have been a direct result of the layup processes and advanced planning.

Some of the earliest Baltek boats were a botch because of poor planning. Both Blackwatch and Egg Harbor were built using Baltek and while the company showed demonstrations that the end grain balsa would not soak up enough moisture to make a difference time proved them wrong. Even when the boats were only a few years old I can remember having to wait for the water to stop dripping from the core to install transducers. These would be mid 80's vintage hulls with no for thought as to leaving solid surface areas for thru hulls etc.

Some 20 years later Viking used a full balsa core hull on their 61. This was built with specific "no core" or solid sections to accomedate thru hulls, intakes transducers etc... These are a more modern hull (early 2000) and I haven't heard of major failures. However time will tell.

All of the new technology is great. (Loran A would suck to still be using) I really hope it works out. However time will tell. I'm fairly sure that the 32 year old hull that we've redone will still be around in another 32 years. I'd like to compare the two if the Nassau 3204 is still around.

Oh and I've got Awlgrip in our bilge. It's still holding up. And if it peels I'll redo it. But you know what,,,,,,, only time will tell.

Buju- I said that in response to pat saying he hates balsa core, no other reason, there was nothing else intended.

And I will still say I dont like paint in bilges! It looks really sharp in certain boats and engine compartments, but you still cant beat gelcoat.

The acrylic can be had at plastic supply houses, or a sign shop supply. It is used for everything from bathroom liners to signs. Its flexible so it wont break, its super light, wont rot, and easy to paint. You can get it thicker for different puposes. Get a clean white sheet and you can even install it as-is and paint it later on when it starts to weather.

We use thinner acrylic for making custom panels, just this week I heated and shaped a piece of .125 acrylic to make a custom base for a GPS install on a small boat that had no room for a GPS, so this acrylic panel made the top of dash area that once housed a cup holder a mounting point for a Garmin. Keeps a brand new boat clean and makes installing a GPS a couple hundred dollar job instead of a $1000 job of grinding and glassing on a brand new dash. Heat a thin piece, prime and paint it and it off the boat, pro set epoxy it into place and a clean up bead of caulking around it makes it look like it grew there.

I stay out of this given my general lack of knowledge, and enjoy picking up the various tips here and there (gotta' go back and get JP's drink mix if its that good).

But, Geez, what did I do?

Quote:
btw- I hate formica!


John F. (as in Formica)

FWIW, a few years ago I bought a fb deck from Craig Mac. As I remember, the deck was at Raybo Marine, and the Raybo guys loaded it into my 83-year old (probably only 79 at the time) Dad's truck for me so he could drive it down. In my book, the Raybo guys couldn't have been more helpful.

Oh yeah-- I really like the boat Yachts101, but am not crazy about cored hulls. [/quote]

I remember that day , I think I even told you that you could probably use the deck as-is.

Did you ever re-core it?

yachts101 wrote:With the new H Grade, major improvements in all significant performance areas have been achieved. Strength properties have been increased by an average of 10% whereas the shear properties (normally the most important property for a sandwich core material) have seen even higher gains. Shear strength has been increased by up to 20% and elongation to break has risen by up to 50%. The ductility of Divinycell H has also been markedly improved making it ideal for applications subject to fatigue, slamming or impact loads. Where a more brittle core material might well shatter or delaminate as a result of an impact, the ductile performance of the upgraded H grade allows it to absorb energy when deflected without structural failure.

Thanks yachts! Gee, I hate callin' you "yachts"; is that your given name or surname?

I really must admit that I don't know the vintage of the Divinycell that I have on hand and, like all products of worth, advancements in technology does bring about better qualities. I'm working, when needed, from stock purchased two years ago from a dealer who had it in stock for who knows how long...

Its good to see that you're elaborating more, (much to Sean's dismay), and look forward to more from you. Which fabrics are ya'll using in your layup schedule?

Br,

Patrick

Raybo-

I remember that day , I think I even told you that you could probably use the deck as-is.

Did you ever re-core it?

Didn't have to. I just ground out the little delamination spots, filled with West, and on it went. Still looks good, and will be coming off this winter when I replace the tank, then back on as is. Thanks again.

John F.

Raybo: Balsa done right will last indefinitely. The problem is that the boat gets sold to a customer who then gets his cordless drill out and adds all of his accessories. That is when the core gets compromised. It is almost impossible to keep from happening with the average boat owner.

You can still remove a cleat or bow eye from a 15 year old balsa core boat and as long as it had good sealant put on it the core inside is dry.
The other HUGE issue is NO ONE ever removes and re-beds thier hardware.

How many of your 31s have rotted wood in the gunwales? I know even Capt Bobby's has some soft spots.

Sadly if every 4-5 years people removed thier deck hardware and re-sealed they would not have problems. Even composite cores will delaminate and the bond will fail when it is intruded.

i remove...redrill oversize...fill with epoxy (thickened) redrill , remount.

randall wrote:i remove...redrill oversize...fill with epoxy (thickened) redrill , remount.

Bingo give him a Cigar.
I used divinycell for my half tower roof worked great light and still strong. I used balsa to replace my wet cockpit core due to all reason stated lose bridge ladder. It was wet all the way to the transom. Relpaced it with balsa but redrilled everything over sized then filled with west and filler's and redrilled. If I ever sell it and new owner adds soem thing and takes short cut Well then screw him he deserves it!! Balsa can be useful It has very good strenght and a lower price then many other cores but has to be treated correctly.

So Yachts do you vacuum bag it???

when you re-cored you could have made the mounting point solid glass, when we re-core a wet deck from the windless or bow railings we make that area solid glass, pack the area around a deck hatch solid glass as well.

randall wrote:i remove...redrill oversize...fill with epoxy (thickened) redrill , remount.

Been doing that for over 20 years, and touting it on the Tips Page for close to 15 years...

The acrylic can be had at plastic supply houses, or a sign shop supply. It is used for everything from bathroom liners to signs. Its flexible so it wont break, its super light, wont rot, and easy to paint. You can get it thicker for different puposes. Get a clean white sheet and you can even install it as-is and paint it later on when it starts to weather.

We use thinner acrylic for making custom panels, just this week I heated and shaped a piece of .125 acrylic to make a custom base for a GPS install on a small boat that had no room for a GPS, so this acrylic panel made the top of dash area that once housed a cup holder a mounting point for a Garmin. Keeps a brand new boat clean and makes installing a GPS a couple hundred dollar job instead of a $1000 job of grinding and glassing on a brand new dash. Heat a thin piece, prime and paint it and it off the boat, pro set epoxy it into place and a clean up bead of caulking around it makes it look like it grew there.

Thanks Robbie, that's some good info.
So it's essentially sheets of molded acrylic resin...
Great tip on the panel repair, sounds clean and easy.
Is it prone to crack easily from applied pressure when drilled?

You guys got all nice all of a sudden! Mark, I haven't seen a picture of the little fat brown one (his express) for a while - do you still have her and if so anything going on?

it does not crack easily at all, you can drill it with standard bits, but they do sell plastic/plexi specific drill bits, never had to use them.

We also did custom engine vent covers for a large Sea Ray with them, beats making custom fiberglass sheets and gives the same outcome, easier on the wallet for the guy paying the bill.

Holds sealant very well also.

I still cant believe I had a different opinion then Capt Pat and Capt Bobby got very upset.

...then Capt Pat and Capt Bobby got very upset.

Don't recall getting upset... I don't get mad; I get even... :^)

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8 or more answers...



Br,

Patrick

that reads funny, its meant to read as "I had a different opinion then capt pat, which got Capt Bobby very upset"

here is that heated and shaped piece of acrylic I was discussing earlier, took all of 20 minutes or so to cut it, heat it and bend it in 2 places.

Slick work, Robbie...

CaptPatrick wrote:Been doing that for over 20 years, and touting it on the Tips Page for close to 15 years...

and you think i learned this where?

Yachts man I like to recomend you to read an article about Cored Hull Bottoms made by David Pascoe on the following address:
http://www.yachtsurvey.com/cored_hull_bottoms.htm
I already read many articles made by this guy and till prove in contrary he is a guy that knows what he is talking about. Just in case that you don't accept Capt.Pat ideas and knowledge and by considering that we all here are "Bertramaniacs" only.
I don´t know very much about building or rebuilding boats. But I am doing a big big rebuilding on my Bertram 31 and for me, "Bertramaniac", the word of Capt Pat is the law, many times proved in practical redoings even for guys like me ,layman on the matter.
Capt.Pat don't need to give me the $20 you earn before, I say this for free and because you deserve a great consideration and admiration of all "Bertramaniacs" (sorry for the word!!!)

Well, Luis, don't jack me up too high on a pedistal; I hate long falls... But thanks for the kind words, I'll try to live up them for you. (Since I can't send the 20 bucks.)

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8 more answers

and you know what they say about opinions!

Just like assholes... Everybody's got one.

Only time will tell................

Yup...

okay raybo first of all you know i owned and drove m77 superboat.a balsa core layup bottom.region 11 apba point winner no problems but there were no fittings anyway.then one day the owner/sponsor took a test ride offshore in a brand new basa core layup cat we were running about 100 to 105mph in 4' waves we slowed to 85 going into a turn center tab up letting her slide the thottleman than drop the hammer and bam it happen without any indication at all.this is the era before epirp and the water was cold.i came to with my lifeline pfd holding my head above water.i realize i was in severe pain and my right hand did not have any feeling or movement my shoulder blade was broken but the owner was 20' from me in much worst condition severe internal injuries (he later had his spleen removed as well as partial intestines)the nav.didn`t have a scratch we were rescured as the boats starboard sponson bobbing up and down went under with the life raft under the deck!!!! as i lay awake each night in neck pain (luckily i got my hand movement back but fingers are numb some days) i had two other break up but they crack first at least you have time to bail out.so i have had a wonderful experiance with basa core as well as my cockpit deck where no hardware existed.i had to redue the entire perimeter of that piece of crap 5 year old aqua tek deck.excuse me for being rash my neck is killing me tonight!!!!!

Hey Rocket... Yeah the "buju" boat is still around, but hasn't really been touched in a few years. My partner in the project is the same guy who I mentioned has been rebuilding that 38' Benchmark. So.. that project took precedence.
I had it (B25) down here in the Keys for a while, and did some serious work on her, but had to move her back to WPB and she's has been sitting around up in Bruce's neighborhood for quite some time now. But she aint goin nowhere...sometime life will get outta the way and work will resume, but until then she's still best viewed in "animated form"...


Bob... Glad you're still around to talk about it.

Bob, thats kind of like a Nascar driver complaining after he crashes into the wall, what does balsa core have to do with what happened to the boat??? Getting in a boat at 100+ mph you are putting yourself at risk, no different in my eyes then going fishing when its rough out and complaining that you got wet that day and things fell apart in the boat.

while obviously no fan of cored hulls i think using a boat that can go 100+ is an unfair test vehicle. tell us a little more about the rescue bob....you a lucky guy.....god must be saving you for something else.

Bob....ain't that C3 disc a bitch. Know the feeling or lack of feeling. After nearly 20 years racing dirt bikes..I did mine up on a stupid mountain bike going about 10 mph or less. Embarressing but true. At least you have a good story behing your injury.

All the talk on cores has gotten me researching this a bit. Any cores on the original B31? Only spot I can think of are the prop strut pads and those look to be marine plywood.(had Anywhere else? Just curious of what spots I need to keep an eye on. (already repared the strut pad)

I've got to find out what the core material was being tested at my sons school. It looked like a multip ply, and was very strong. You could not break this material easily with your hands.

raybo this was the second cat out of the mold built full race (no interior just cross bars) she split from the nose of the port sponson to the thorttleman position.split apart so to speak.was not like a hole in the boat and time to bail out.stricly a balsa core lay up problem.this is a race boat built to race not misuse of a pleasure boat.skater,viper and outer limits all went to kevlar hand lay up with carbon fiber structuals.unfortunatly in the apba world series (key west) two men went down with the ship and drowned that was the last of balsa shit and the use of canopys with oxegen masks for cats.
gplume the can`t operate on it seems like i was 30' in the air and came down on side of helmet and shoulder blade.the neck must have done a 180 degree and c3 gave way along with the nerve pinch against it very painful.being in that cold water with nobody around didn`t help your spirts either this was not a race just practice.300dollars a day and all the excitment you wanted what a price to pay -----idiot.

sorry about your accident bob, but it was a hundred years ago--- and they still use balsa core in race boats and canopy cats

you had better stop using Phoenix- it has that balsa core in the deck!

not mine oem 3/4" marine plywood with 1/8 lay up on top and 1/4" layup raesin on bottom i have piece for you to examine no more arguments.basa wood is used for making toy airplanes,you remember with the plactic propellar and rubber band!! kevlar is for manly things like bullitproof vests,race boat construction---ok