Ok I have looked every place i can think of and I can't find the answer anyware, so I sory in advance if this is a well known thing. I got a Solcat 18 for free from my uncle, but it has some soft spots in the hulls. I did a whole lot of reading all over the internet as well as here about how to fix hobie cat hulls, but when I started the process of drilling my holes for the resin, i found that solcats do not have a double hull. is this correct? am I just seeing things, and if not how do i go about fixing the hulls? This boat is older, last time it was licenced was 1982. I don't want to scrap it, i got almost everything for it. My Dad also has the same boat with the same problems, just not as bad as mine. anything you guys think will help would be a huge help as I am just lost. thanks

I'm not familiar with the design so it would help if you could tell me if it's plywood or fibreglass.

This may help.
http://www.turbolink.co.uk/jlasurveys/osmosis.html

I'm pretty sure they're solid fiberglass construction (without a foam core) - just like the Nacra 5.2's of that era.

Repair is not going to be terribly easy but it can be done (anything can be done with fiberglass). I'm pretty sure the deck is similar to the hobie 16 style - that it is a solid piece that has a lip that slides down over the hull. If the soft spots are large and wide, you are going to have to get large scale access to the inside of the boat...that means either cutting large access holes in the decks to be repaired later or removing the deck entirely.

You would then glass in reinforcements and/or horizontal stringers to beef up the aging fiberglass from the inside. This is not an easy (or terribly inexpensive) task. I'm sorry to say that you would probably be better of searching for a newer boat that you could reuse most of your gear on.

Try reading this:
http://www.hobiecat.com/community/viewtopic.php?t=1156

If the hulls are foam core with a layer of glass on each side this method will work.

When drilling, you are only going through the top layer of glass to get to the foam. The Git Rot method will epoxy the sandwich back together and the strength will return.

Jake, thanks for the information.
as for the cat, it looks like she has is a solid piece of fiberglass that has a lip that slides down over the hull. so were do I cut the access holes and how big can they be, also, how would I go about removing the entire deck? It looks to me to be fairly solid were it is attached to the lower part of the hull. Thanks to all who contributed to this post.

Before we get into that...where exactly did you drill holes and not find a foam core?

(We still need someone that knows Solcats to chime in here about the exact hull construction)

Also, originally he said the soft spots were in the hulls, but does he mean the hulls or the decks?

ok, i drilled 2 holes in the deck about 4' from the rear of the hull. i drilled an 1/16 test hole and went just through where I thought the outer layer of fiberglass would be. i then pushed a nail down to find out how thick the foam was and it just kept on going in. I then went arround to the back of the boat and looked in the drain holes.( I can't get the inspection ports off.)and what I saw was what I thought to be fiberglass cloth resined on to the inside of the deck(where I had drilled) and the inside of the hulls. I may be wrong, and this may be normal, but I am so new to this that I am not sure what I am dealing with. When I got the boat a neighbor came over and told me that the soft spots were not a big deal and about how to fix them in a hobie like he had. But now that I get in to do that work I find that it won't be anything like I thought it would be. Also THANK YOU for all the help, I would be lost without it. Also, my Dad is reading this post to help him fix his own soft spots.

You have one of two different kinds of hull construction. I know that the early Nacra catamarans were solid fiberglass and the hulls and deck were probably about 1/8" to 3/16" thick with just fiberglass and resin (probably thicker in areas like cross beam mounts). The other type of construction, very common in all the Hobies and all post mid-80's catamarans, is "foam core" construction. This has a thin inner layer of fiberglass (probably 1/8" or less), an internal foam core (usually tapered at the edges of the piece but up to 3/8" thick), and then an outer fiberglass layer usually around 1/8" thick or so.

the instructions you got for repairing it "Hobie style" is to repair a soft spot that results from the foam "delaminating" (aka breaking away or crumbling) from either the external or internal fiberglass layer or both. To repair this you drill several holes in the soft spot, twist something around to futher break up the foam inside the area, and then fill it with epoxy or polyester resin to re-fill the middle to reconnect the inner and outer fiberglass layers.

What I suspect you have (again, unconfirmed) based on your drilling experience, is that you have a solid fiberglass construction. Soft spots in this case would mean that the resin and fibers have weakened over time (absorbing moisture, repeatitive stress, etc.) or that some internal reinforcment has broken away from the hull. You will need to either reinforce the areas in which the laminate has weakened or repair/replace the internal reinforcement that has been damaged (bulkheads or stringers). This kind of repair is going to involve cutting large holes in the deck, reinforcing the area, then fiberglassing the large cutouts you made back in place.

Bottom line though, is that we need to figure out for sure what kind of construction you are dealing with. It could be that the foam is so far gone that you thought you went through to the inside of the boat when you have just gone through the first layer...dunno. Could you see light from the inside through the holes you drilled?

If it is on the deck, why not cut in new inspection ports in the soft area. That way you can see how it is made and reinforce it on the inside around your new port. I did this years ago on a old hobie. Then after sailing I would open the ports and let it really dry out after each sail in the sun. Just a thought.