airex core hull

mrkeith · #1 (**permalink**) 01-09-2007

hi, i have a boat which has an airex core hull (1980 model). how can i find out if the core is dry or taking on water? is there an easy way w/out doing anything too invasive such as drilling etc?

sailingdog · #2 (**permalink**) 01-09-2007

If the boat is on the hard, tapping with a plastic hammer or screwdriver handle can tell you quite a bit. The areas that have water intrusion will sound different than the areas that don't. A moisture meter will do the job, but you really have to know how to use one for that to be effective.

mrkeith · #3 (**permalink**) 01-09-2007

thank you. what do you do if you do have water intrusion?

paulk · #4 (**permalink**) 01-09-2007

Just to second Sailingdog's caution about knowing how to use a moisture meter... We had one surveyor check out our hull below the waterline. He put his meter on the side of the hull, (the boat had been hauled out for several months) and it read wet almost off the scale, all over. He suggested we walk away from what appeared to be a sopping mess. We brought in another guy for a "second opinion". He did what the first one did, with similar results. Then he went up into the boat, and put the meter against the inside of the hull where he could, all over. Bone dry. He explained that there was no paint on the inside of the hull, but the bottom paint on the outside of the hull had apparently absorbed enough moisture from rain or dew to register on the meter. The fiberglass was fine. I guess the moral of this story is that a little knowledge is a dangerous thing. The more you know, the better your decisions.

mrkeith · #5 (**permalink**) 01-09-2007

interesting. i have also heard that certain types of antifoul retain water for up to 21 days thus using a water meter is ineffective until a month later

so what do you do then? test the insides and top and see if there is a problem?
also, i m guessing it takes a collision or crack to cause the damage to the hull to let such water in? so cant you just survey the hull for significant damage and the would give you the clue?
thanks for the advices

camaraderie · #6 (**permalink**) 01-09-2007

mrkieth...to answer your question about what to do if REAL moisture intrusion is found on a cored hull. The anwer is walk away from the boat in my opinion.

paulk · #7 (**permalink**) 01-09-2007

Negative on needing an obvious structural issue to have water intrusion. If you read the used boat buying threads you will find frequent reference to blisters, wet core, and delamination. These are all caused by water infiltrating the supposedly impetetrable gelcoat, or by water getting in through screw holes, tiny cracks (have you ever dropped a winch handle?) or past poorly installed (not properly caulked) fittings, like cleats, blocks, winches, and shrouds. We had a screw hole on the INSIDE of our hull which, over the space of 20 some years of spashes, rain, condensation, sweat, bilgewater, you name it, caused delamination of the balsa core of our boat in a roughly 3' diameter area. Tapping the entire hull with a small (but hard) rubber hammer every few inches is the best way to find problems that have grown that big. Moisture in the hull or laminates is a precursor to possible problems later. Fixes can vary from rebedding fittings to stripping the entire hull. It all depends.

sailingfool · #8 (**permalink**) 01-09-2007

No thread regarding wet hulls can be complete without the obligatory reference to David Pascoe's screed on the subject http://www.yachtsurvey.com/cored_hull_bottoms.htm

I read these articles 6-7 years ago and they put cored hulls on the NoGo list for me. A friend of mine who just had all the Airex core in his Famous-Maine-Name 42 replaced now agrees.

mrkeith · #9 (**permalink**) 01-10-2007

thanks for that. how did he determine he had a problem? what did your friend do when he replaced it on his 42? it probably was expensive?

sailingfool · #10 (**permalink**) 01-10-2007

Quote:

Originally Posted by mrkeith

thanks for that. how did he determine he had a problem? what did your friend do when he replaced it on his 42? it probably was expensive?

I beleive he had some minor blisters after his second-third season which led a new surveyor to the discovery. The work involved peeling the outskin, removing all core, drying the boat for 9 months, new core, new skin, fairing. He paid about $18,000 by holding the yard to the quote they had provided initially - the yard ended up wanting about 50% more due to surprises.
The original surveyor did not detect the problem, which the original owner doubtlessly know about...