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Hull Foam

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(@Anonymous 37749)
Posts: 487
Topic starter
 
[#18868]

There has not been much discussion about the foam, in the foam/fiberglass sandwich that makes up the Hobie hulls. There has been lots of discussion about the delamination that results from the failure of that foam. And there have been suggestions that the foam of the early ‘80s was of lower quality, and specific discussions about the “red glue line” hulls and changing hull weights.

So what is the history of the Hobie hull sandwich and the foam filling???

How has the foam and the sandwich construction changed over the years?
Has the construction consistently improved?
Have past efforts been made to improve the bonding between the foam and resin?
Have past efforts been made to reduce the damage caused by internal hull moisture?
Why don’t H-16s have factory installed ports to allow dry-out of the hulls?
Has the thickness of the sandwich change over the years?
Is susceptibility to ‘walking-on-the-hull’ damage a significant concern, and has that susceptibility changed over the years?

Let the discussion commence!


 
Posted : November 17, 2006 4:41 pm
hobie1616
(@hobie1616)
Posts: 2117
Captain Registered
 

Take a look at the Hobie Forum to answer most of your questions. Go through the 16 forum first.

http://www.hobiecat.com/community/index.php?c=N


 
Posted : November 17, 2006 7:47 pm
(@Anonymous 17342)
Posts: 885
 

I loved my little Hobie 14... but I am really looking forward to not having to worry about stepping on my hulls with my Nacra.
I know that the idea of inspection ports sounds like a good idea, but they leak sometime which actually furthers the problems.
It seems to me that after 30??? someodd years of making a boat there could be a way to prevent the delam.


 
Posted : November 17, 2006 8:09 pm
hobie1616
(@hobie1616)
Posts: 2117
Captain Registered
 
Quote
It seems to me that after 30??? someodd years of making a boat there could be a way to prevent the delam.

The current discussion on the Hobie forum indicates that boats built after 1980 have a very small incidence of delam problems. The exception is when the boat is stored with the drain plugs in for extended periods of time.

http://www.hobiecat.com/community/viewtopic.php?t=5327&sid=9436946f7311aaa47554eb9524d8f38d


 
Posted : November 17, 2006 8:25 pm
(@flatlander)
Posts: 1108
Master Chief Registered
 
Quote
And there have been suggestions that the foam of the early ‘80s was of lower quality, and specific discussions about the “red glue line” hulls and changing hull weights.

From what I've been told by reliable sources, all the 16's I've seen over the years and information from the forums;

Late 70's decks we're prone to softness. Don't know why. People complained. The '80, '81 (I bought one new), were tanks. Solid decks and over minimum weight. People complained. Weight came down in '82, '83. Solid decks. Coleman boats begin in '84 & '85 and identified by serial number, Coleman sticker on the transom and red glue in hull to deck seam. Weighed at minimum weight. Solid decks. Since then weight has fluctuated a bit, and decks are stout (depending on care or lack of).

If you leave water in the hulls all bets are off.

When looking to buy ANY Hobie 16 check the decks, if they are soft, walk away. There are a cajillion more to look at.


 
Posted : November 17, 2006 10:51 pm
(@Anonymous 15703)
Posts: 1312
 

If you get the boat cheap enough and its only the decks that are soft its not hard to cut the decks off put and some foam or 4mm ply bulkheads in. Then turn the old decks over wessystem 8mm davinacell foam, then cloth on. The foam can be ordered with slits so that it curves to the shape of the old deck easily and doesnt pull the deck out of shape. Then make a lip around the cut with foam and cloth sit the deck back on wessystem the deck back on. You can now dance on the boat for hardly any extra weight. Avoid deck ports anywhere near where you might put weight. Ive just done all this including the cheap boat
regards <img src=

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Posted : November 18, 2006 3:39 pm
(@mbounds)
Posts: 1823
Master Chief Registered
 
Quote
Late 70's decks were prone to softness.

Yes, but only after many years of (ab)use - the Hobie warranty is five years. I don't know of any warranty claims for delamination. Matt Miller may have some history on this. I owned a '78 and raced it hard for six years. No problems.

Quote
Don't know why.

Speculation is that the foam core did not allow the layup to adhere to it as well as later foams. Matt Miller confirms that the type/brand of foam was changed in the '80's.

Quote
People complained.

ORLY? If you buy a boat that's out of warranty, then you have nobody to blame but yourself for not inspecting it thoroughly.

Quote
The '80, '81 (I bought one new), were tanks. Solid decks and over minimum weight.

Min weight at the time was 340# Most boats of that era still weigh less than 355#. Boats were not regularly weighed then because the nationals had provided boats.

Quote
People complained.

About what? Most people had no idea what their boat weighed.

Quote
Weight came down in '82, '83. Solid decks.

Nope. Manufacturing process was changed for the 1984 model year which resulted in a significant reduction in weight. Class min weight was changed in 1985 to 320#, where it remains today.

Quote
Coleman boats begin in '84 & '85 and identified by serial number, Coleman sticker on the transom and red glue in hull to deck seam.

Wrong again. Coleman bought Hobie Cat in 1976. Red glue seam was indicative of the 1984 manufacturing process. Hull graphics changed in 1984 and included the Coleman stickers. Coleman sold Hobie Cat in 1988.

Quote
Weighed at minimum weight. Solid decks.

Actually, the '84/'85 boats were less than minimum. I owned an '84 that had lead shot in the rear pylons (from the factory) to bring it up to minimum. I own an '85 H-14 that weighed 8 lbs less than minimum before I put a dolphin striker and a trapeze on it. My '84 16 was a bit fragile - two pylons came loose and had to be repaired.

Quote
Since then weight has fluctuated a bit, and decks are stout (depending on care or lack of).

Actually, weights crept up from '86 to early '90's because of the warranty claims for fragility. (I owned an '89 that weighed 345#) In the meantime, the H-16 became an ISAF International Class, and the class rules became subject to ISAF oversight. In 1990, Hobie Cat stopped providing boats at nationals and boat weighing became more commonplace. In 1991, sailors and ISAF exerted pressure on Hobie Cat to produce boats at minimum weight, which they agreed to. Since '92, boats have been generally at minimum weight, and the weights of the hulls are engraved behind the rudder pins. (Most hulls weigh between 68# and 72#)

In summary, delamination occurs on the 1970's boats because they're old. Nearly 40 years of flexing on the decks breaks down the bond between the glass and the foam. Once it starts, it's like cancer. You can fix it in one area, and it'll pop up in another.


 
Posted : November 18, 2006 4:32 pm
(@flatlander)
Posts: 1108
Master Chief Registered
 

Thanks for ALL the clarifications, Matt.

What do they say? Only beleive half of what you read <img src=

alt=

/> <img src=

alt=

/> <img src=

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Quote
I owned an '84 that had lead shot in the rear pylons (from the factory) to bring it up to minimum.

This is interesting. My first instinct would say add the weight at the front pylon. Any particular reasoning behind this that you know of?

Thanks, again


 
Posted : November 19, 2006 10:54 am
CMerrell
(@cmerrell)
Posts: 206
Member
 

<img src=

alt=

/>


 
Posted : November 20, 2006 7:41 am
CMerrell
(@cmerrell)
Posts: 206
Member
 

Don't know what happened to my text!

Attended a regatta this year in which the bow of a '70s-era H16 snapped off. The deck foam was obviously brown and deteriorated but the hull foam/glass was pristine; looked like it had just left the factory. I was impressed that the foam of a 30 YO boat would look that good.


 
Posted : November 20, 2006 7:45 am
mmiller
(@mmiller)
Posts: 1237
Master Chief Registered
 

Just a bit more on the foam issues...

Back in the early days Hobie Alter was making balsa core surfboards. He created the foam core board process and his buddy Gordon Clark took on the business of making the (Polyurethane) foam. The foam Hobie used in the cats was the Clark Polyurethane foam for many years. Clark used to make the foam in large loafs, then the loafs were sliced like bread. Lower layers were more dense and throughout it varied. That seems to have made some of the difference over the years. We quit using Clark foam back in the early 80's. We have been using a PVC foam for many years without the original problems from the 70's.

Weights...

In the 1984 model year Hobie Cat took some steps to lower the weights of hulls. The change in process was marked by the addition of a red dye in the glue seam process. The new process involved a different glue seam technique, better control of excess resin and in some cases (Hobie 18) a change in the amount and location of the glass layup. The Class rules were fixed and needed to change, but Hobie Cat began using the new processes. To keep the hull weights at the minimum levels per the class rules, some boats had lead shot added in the rear pylon (for a short period). Why rear?... weight aft is a GOOD thing. Some people were able to chip out the weights after the rules were changed. Hobie 16 class weight went from 340 to 320 pounds.


 
Posted : November 20, 2006 1:23 pm
(@Anonymous 11804)
Posts: 390
 

84 H16 with red glue. Weighed 321 at the 93 Nationals.
The shoe is cracked as you can see.
I repaired both hulls this spring with West System.
The decks on this boat are solid. Good for another 10 years of Fleet racing.
[Linked Image]


 
Posted : November 20, 2006 2:33 pm
 Karl
(@sogncab)
Posts: 3551
Member
 

When was the last time you bought anything, and expected it to last more than 10 years? I plan on trading/selling my H16 in 2008. I like new things, can't afford a new truck at 50k that often so my as well replace the boat every three years for a few thousand dollars.


 
Posted : November 23, 2006 3:46 pm
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