Why did Hobie discontinue the shroud anchor plates?

Has anyone found a source for these? I am in urgent need. Thanks in advance.

Welcome to the club. Unless you find a wrecked boat or decide to take the one on your shroud to a fab shop to copy you are screwed and your hulls will eventually fail.

The plates were a stop-gap measure... Fiberglass in the hull (connecting the decks to side walls) is the ultimate answer that we ended up in H18 production. You can do that too.

_________________
Matt Miller
Former - Director of Parts and Accessory Sales
Warranty and Technical Support
Hobie Cat USA
(Retired 11/7/2022)

Matt, that's actually really interesting, I never realized that Hobie made a change to the production process on the later boats, rather than (or in addition to) using the plates. So that would suggest that it was determined that the epoxy joint between the deck and the hull was a failure point/weak point, and that additional glass was needed to better reinforce the joint? I had thought the purpose of the plates was more to do with spreading/transferring the load from the hull lip to the hull side more effectively, i.e. that the lip design was the problem, not the joint between the hull and deck.


Also, I think the idea that you're doomed to hull failure without the plates is a little extreme... If you have an early - mid 80's boat without them, you may be in trouble, but if you have a 70's boat or a late 80's boat or newer, the boat will be fine. Just be sure to inspect the hull lips once or twice a season, and if they start to separate flip the boat over and fill the hull lip with epoxy. Maybe add some epoxy on the inside too, or if you're really concerned, Matt's suggestion to add glass inside would surely take care of the issue.

_________________
Mike

'79 H18 standard 'Rocketman II' sail #14921 RIP
'78 H18 (unnamed) sail #14921
'08 H16 sail #114312
'97 H21SC sail #238

I've inspected at least 12-15 boats from every age as well as having seen someone rip a bow off because of the beam ripping the lip off. They almost all have cracks in the hull under the beams and take on water. You don't notice it as much when the boat is on land, but on the water a loaded boat is prying open that crack. It's only a matter of time + stress cycles before that crack grows and leads to total failure. I have no doubt that the boats were built better in later years but that was a long time ago and the one thing all the boats have in common is polyester resin, which during the life of a typical hobie, has absorbed a lot of water due to the pretty much constant 100% humidity in the hulls. In this weakened state the strength of every part of the hull becomes in question. If you only sail in under 10kts and never go out in heavy conditions you will probably be fine for a long time, but if you sail these boats as they were intended, the beam connection is the grim reaper for the boat.

The one guarantee with the anchor plates is that for the beam to tear off off the lip it's going to have to rip the plate screws completely through the sides of the hull. I'm not positive but it also appears that the later model H18s all had anchor plates on the beams from the factory anyway. At least every super late model boat I've seen has had full plates on the boat.

One possible solution to having the pretty factory plates is to use a piece of stainless strap and just attach it to the sides of the hull vertically under the beam bolt. I've seen that on a boat before and it works.

Technically, the ultimate solution is to insert a bulkhead in the hull under the main beam area. It is possible, but difficult. The Hobie 18 is one of the few boats I know of that does not have bulk heads. Nearly all current and recent off the beach catamarans have bulk heads and most also have sub decks.

The anchor plates are a stop gap measure. I have one of the later boats (late 1990’s) and it still has hairline cracks around the beam area. I have put shroud anchor plates under the front beam, sidestays and rear beam for total security. I also reset my inner beam castings on both front and rear beams so they don’t move inside the beam. This aids greatly in platform stiffness. The internal castings are riveted in by the factory and the rivet holes elongate over time. I removed them, cleaned them up, then bolted them in with 6mm cap head bolts. I then epoxy glued in the beams. All of this adds to platform stiffness and takes load off the outer beam bolts of the front beam. Note that the better the rear beam is attached, the less twist and load there is on the front beam bolts. Stiff rear beam = stiff platform. (Look at the enormous size of F18 and Tornado rear beams in compassion to their front beams).

Enjoy!

_________________
John Forbes
Hobie 18 Reimagined
Sail # 490
Boat name: 18@heart
http://www.hobie18.fun
https://www.facebook.com/Hobie18catamaran/

Hobie may have considered the anchor plates to be a stop-gap measure, but at least in the US, they never stopped installing them in production after they were first introduced around 1986. To me, that means Hobie always considered them to be necessary.

I have also seen boats that have had the bow break off and also owned a boat that had severe cracking under the flange. The problem is not an issue of the bond line between the hull and deck failing (which could simply be re-epoxied together), it is a problem of the fiberglass actually cracking in the corner of the lip. The glass just wasn't thick enough on some boats. Once the hull cracks, it loses its structural integrity- think of the hull cross-section as a triangle. If one of the corners becomes disconnected, the whole triangle collapses.

A bulkhead could be added to the hull. The concern that I would have with that approach would be that you could actually end up introducing only a very localized area of reinforcement and that could cause a stress riser at the crossbar that still leads to failure. On my boat, I chose to reinforce by adding stringers to the sidewalls of the hulls over an 8 foot length. This stiffened up the hulls over a much larger area. After the repair, at 200Lbs, I could lay the hull on its side, stand on the side of the hull and feel zero flexing.

https://www.hobie.com/forums/viewtopic.php?f=13&t=49780&hilit=Hull+reinforce&start=15

sm

Hi SRM,
Your stringer idea is excellent. I’m sure that will fix a lot of problems for years to come.

My bulkhead idea was purely to hold your “triangle” together which in turn will take load off the bolt area.

There are some good ideas for others to learn from.

If only we could buy new hulls and adopt these ideas.

_________________
John Forbes
Hobie 18 Reimagined
Sail # 490
Boat name: 18@heart
http://www.hobie18.fun
https://www.facebook.com/Hobie18catamaran/

I was highly involved in getting the patch added to the 18s in the late 80's. It was not the thickness of the glass, but rather the width of a patch in the area. The width was reduced to help in lightening the 18 in 1984 (Red Glue Seam).

This narrow patch caused loads to hit the corners on the indented area and that allowed cracks. Especially when SX wings were in use. By going back to a wider patch would work, the larger post glue deck to hull patch was insurance which allowed us to extend the warranty on the hulls for a longer period. The bracket at that point became redundant, but not something we considered pulling off the boat. That was also additional insurance.

Adding patches and also at the rear would be ideal.

_________________
Matt Miller
Former - Director of Parts and Accessory Sales
Warranty and Technical Support
Hobie Cat USA
(Retired 11/7/2022)

Thanks Matt Miller. We appreciate your knowledge and input. I’ve added larger corner patches to my mainsail and jib for the same “added insurance” reason.

_________________
John Forbes
Hobie 18 Reimagined
Sail # 490
Boat name: 18@heart
http://www.hobie18.fun
https://www.facebook.com/Hobie18catamaran/