Your go-to source for performance boating.
HomeMattBlogCosker on Mystic Delamination: “I Don’t Expect to See Any Other Issues.”

Cosker on Mystic Delamination: “I Don’t Expect to See Any Other Issues.”

With the recent delamination problems experienced by JBS, a 50-foot-long Mystic turbine-powered catamaran owned by Jeff Stevenson, speculation on Mystic delamination issues has run rampant. Just about everyone in the go-fast world, particularly online, seems to have an opinion on the matter, which is only natural given the big splash Mystic has made in the past few years.

“The Internet can be your greatest friend or your worst enemy these days, with sometimes unqualified people making judgments on situations they have no firsthand knowledge of,” said John Cosker, the founder and owner of Mystic Powerboats in Deland, Fla. “But hey, it’s America and they are certainly entitled to their opinions.”

To get Cosker’s take on the situation, I asked him four questions.

How many Mystic 50-foot catamarans have been built to date?

We have built 11 of the Mystic 50s to date.

How many of them have had problems with delamination? Which boats were they?

Hull No. 4 was Jeff’s (Stevenson) first boat and it had a delamination problem.  This initiated because of a lamination error on our part where the vacuum bag did not go down on the core bond laminate fast enough and the epoxy resin began to gel before full vacuum was pulled.  Because of this, we didn’t get a good core bond.  In the Miami race the boat began to have an issue on lap three and the team kept running it until lap 11 when the bottom laminates were stripped off the core.  If the boat had been pulled out of the race in lap three, damage would have been much more limited.  Be that as it is, I took that hull in on trade and put Jeff in a new hull that was being built on spec so he could get back out on the course quickly.  We then fully repaired his old boat by building an entirely new sponson in the mold and grafting it back onto the boat.  That hull is now for sale.

Have you found any sort of common denominator in the problem?

His (Stevenson’s) current boat, hull No. 6., had a problem with the rear starboard lifting strake on the run to Bimini and back. The boat was delayed in getting back to our shop due to some other issues, and we only had a few days to repair the strake.  Unfortunately in our haste to fix it we missed some of the damage and it cracked back out at Lake St. Clair.  It wasn’t a large amount of damage—we may have been able to be fixed the night before the race—but both Jeff and I judged it wasn’t prudent to take the chance.

What’s the long-term solution?

Since these two boats were built we have changed our lamination practices by not vacuum bagging both running surfaces individually but putting the two running surfaces under separate bags to ensure the there is not too much “out time” before full vacuum is pulled.  Due to this change, I don’t expect to see any other issues like this appear.

None of our other boats have seen this issue.  We had some minor cracking on the lifting strakes on the forward sponsons of a couple of the boats but we changed the structural arrangement locally in that area which has eliminated that issue.

One thing to point out here is that our boats consistently go out and run in a range from 180 to over 200 mph every time they are on the water.  The bottom pressures in a speed change from 150 mph to over 200 mph nearly double.  Because of the size of the boat it is able to run over 180 mph in the open ocean illustrated by Jeff Stevenson running over 180 mph back across the Gulf Stream in the Miami-Bimini,-Miami run.  In these situations the bottom loadings go up exponentially.

Our boats have been involved in accidents where there have been no injuries, and the boats held up exactly as expected with minimal damage.

We will continue to strive to push the envelope of offshore performance while always keeping safety in mind.  We have learned from any mistakes we have made and have stood behind our product to the best of our ability to keep our customers loyal to our brand.