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Old 24-01-2009, 15:30   #16
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Originally Posted by CarlF View Post
Twisty,

Here are some thoughts:

Solid fiberglass (no core). No core problems! But you want it thick enough that it hasn't fatigued due to flexing. Very early fiberglass boats built in the '60 and '70s were overbuilt because people didn't understand the material very well. These 40 year old hulls are as strong as new. Since the gas crisis in the early '70s it's become much more expensive to build solid boats so many "price" builders moved to cores - at least in the deck. Also, boats that need to be light (catamarans) need to use cored construction for performance.

Blistering bothers both solid and cored boats. This happens when water get into the fiberglass skin and reacts with the resin. Most common in boats from the '80s. This could be fixed but it was expensive. Boats built in the last 15 years or so have epoxy barrier coats and use more water resistant resins so the problem has pretty much gone away. The good news is that if the boat is more than 10 years old and hasn't blistered (or blistered but been well repaired) it's not likely to start.

Cores:

Very early or very cheaplly boats sometimes had cores of plywood or mystery wood. You're unlikely to find a boat with this core that hasn't either been repaired or been cut up with a chain saw.

Fiberglass with end grain balsa is usually fine if the builder was a quality builder who made sure that they got good adhesion between the fiberglass and the balsa. During the last 15 years most cored boats were built with a construction method that used a vacuum to push the fiberglass hard onto the core. This has helped a lot but the old hand method was fine if carefully done.

The biggest problem with cored construction is where a hole is drilled to mount something and the core wasn't removed near the hole. Unfortunately this is a very common problem with lower quality builders or when later owners weren't always watchful when someone approached their deck with a drill. Even a hole for a bimini snap can cause problems.

Having said that, the great, great majority of end grain balsa cored boats from reputable builders don't have a substantial problem. Surveyors are pretty good at finding core problems. This is probably the biggest "walk away from the deal" survey problem. You do not want to take on a major core repair!

Foam cores were viewed by many to fix balsa's problems but has problems of it's own. Again, a good builder will turn out a trouble free boat. Foam is less bothered than balsa by the "drilled hole" problem.

Here's a petty scary site with lots of pictures of badly built boats. Don't let it discourage you. Almost all of the examples are from lower quality builders and most are fast motor boats (where slamming puts even more strain on a core). Rule #1 - buy the builder not the boat.

Yacht Survey Online: David Pascoe, Marine Surveyor

Carl
Carl,

Thank you for your explanation. This is exactly what I was looking for.

I wish I had taken pics of the cat I saw yesterday, it had obviously been repaired a couple times. With one of the 'repairs' it had obviously hit something hard, I would guess a rock, on the front lower corner, starboard side and someone had done a patch job on it. I guess my point is I don't want something that has been "patched" but I want to be able to do a patch job in a hurry if I absolutely have to. Does this change what I am looking for in anyway?
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Old 24-01-2009, 16:58   #17
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You're extremely unlikely to have a sudden fiberglass problem - unless you hit something very very hard. The most common reason for boats to sink is that an old rubber hose lets go while no one's around and the seacock wasn't closed.

If the patch was done by someone who knew what they were doing, it's probably stronger than the original. It's the stuff that SHOULD have been patched but wasn't that causes the nightmare. Figuring all that out is what surveyors are for. Do find out if the boat ever sank or partially sank. Stay away from those.

You least risky solution is probably an 80's or early 90's boat from a well known builder that needs a lot of cosmetic work that you (and your son) can do yourselves.

Don't worry about learning how to fiberglass. It's not hard but surprisingly inexpensive to let a pro do it. The expensive stuff is sanding and painting because it takes a lot of hours. Do that yourself and you'll save a lot of money.

Glad you liked the cat. Remember, you don't even have to use the sails for the first few years. And Dave's right. Any cat will be cored or have some form of light weight construction.

Carl
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Old 24-01-2009, 22:51   #18
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Quote:
Originally Posted by CarlF View Post
You're extremely unlikely to have a sudden fiberglass problem - unless you hit something very very hard. The most common reason for boats to sink is that an old rubber hose lets go while no one's around and the seacock wasn't closed.

If the patch was done by someone who knew what they were doing, it's probably stronger than the original. It's the stuff that SHOULD have been patched but wasn't that causes the nightmare. Figuring all that out is what surveyors are for. Do find out if the boat ever sank or partially sank. Stay away from those.

You least risky solution is probably an 80's or early 90's boat from a well known builder that needs a lot of cosmetic work that you (and your son) can do yourselves.

Don't worry about learning how to fiberglass. It's not hard but surprisingly inexpensive to let a pro do it. The expensive stuff is sanding and painting because it takes a lot of hours. Do that yourself and you'll save a lot of money.

Glad you liked the cat. Remember, you don't even have to use the sails for the first few years. And Dave's right. Any cat will be cored or have some form of light weight construction.

Carl
Around here it is the hose/pipe to the baitwell that someone bumped just wrong while working on something that usually sinks them. Seen it, family of 5 out on a trip to the stream to do some fishing. when we got to the the stern was under. But thats another story.

I get what your saying about the patch being stronger than the original. being a car person you always knock on a known repair to see what was done to it, I found myself doing that with the cat yesterday. LOL It seemed like it had the benefit of a lot of supporting material around it which made it a lot stronger than the original build. I can lay glass so I am not worried about making a repair, I am as you mention worried about getting my hands on a boat that someone repaired with out the proper knowledge to do so all this information will come in extremely handy. Please if you can think of anything else let me know.
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