I have been told by a few local sailors that the hulls of Prindles and Hobies gain weight with age? meaning they absorb water. is this a true fact? and if its true can the hulls be dried out??
thanks,
Darrell

Dunno if it's a fact, but I always kept the inspection ports open when not sailing.

I'm pretty sure fiberglass can absorb water and the foam core definitely can.

Drying is possible. Repair guys have to do that before making glass repairs as well. I think this is because the resin are hydrofobic. Just store the hulls in a dry (warm) place for a few weeks. With good ventilation and all inspection ports open

Wouter

If this is the case when I repaint the hulls has anybody resprayed the interior with some sort of poyly or something similar would this in actuality be effective in keeping the hulls stiffer ? Bob G

Most PVC foam cores used in today's cat construction do not absorb water. However, polyester and vinylester resins are not completely water proof and will absorb some water. Yes, they can be dried out - warm heat and low humidity for a lengthy period will do it. Epoxy resins are more resistant to water absorbtion but they are not perfect either. There are some additives availalbe for epoxy resin that help it have additional water resistance. Most barrier coats used on monohulls that remain emersed in water full time use and epoxy resin base.

Most water absorption happens when the hulls are immersed in water for very long periods. Unless you leave your hulls with lots of water in them constantly, or leave your boat on a mooring with no barrier coat on the submerged portions, you generally have little to worry about.

Were they trying to sell you a new, or newer, boat? If you have doubts weigh your boat. Our '93 H20 weighs right at minimum weight.

Where are some typical places that have an adequate sling/crane type scale?

Also, if using the widely published (incl. on this site, IIRC) method of curing hull delamination via the West Systems Epoxy Filler, injected into shallow holes drilled on 2" centers, WHAT IS THE APPROX. WEIGHT GAIN PER SQ. FT. filled?

Thanks in advance.

The resin and fiberglass are capable of absorbing upto 1/2 their weight if they are stored in the water. Desert weather for a few weeks can dry most or all waterweight gained by a catamaran. You should have a way for the inside moisture to evaporate, like a porthole.

In the case of fiberglass boats, does most of the water absorption happen as a result of water inside the hull or exposure to water on the exterior of the hulls? I assume that it is more from water on the interior, where the fiberglass is not finished. But I have heard that even gelcoat does not prevent fiberglass from absorbing water.

Also, does anybody know how much weight a wood boat would gain when stored in the water? Traditional wood monohulls, and also modern wooden cats made with WEST system? Like, would a WEST system wooden boat absorb proportionally more or less water than a fiberglass boat?

thanks all, it appears that i have brought up a pretty good topic, I will be "drydocking" my Cat this coming september through October, the winds are pretty much dead during this time as we anticapate typhoons, not a good time to have your cat parked on a beach, so I plan on repairing any hull damage that happened during the season, but I really want to totally dismantle the entire boat just to see if there are any problems arising at all. I would like to "redo" the bottoms gel coat and get rid of the scars from all the beachlandings, I would appreciate any input on such a task. I believe I saw somewhere a KIT to redo the bottom scars but not sure where I saw it. I also have a second set of rudders that I want to refinish in some sort of Plaid material, but Im having trouble locating the plaid material that I wish to use, (something like what Paul Bunyon wore) if you no where to find any plaid type paul bunyon type fabric manufactureres please include a link.

thanks for everybodys help..

regards,
Darrell

seriously though do you think that storing the hulls inside a warehouse, with the hatch and drain plug open will dry the hulls in a couple weeks, with outside humidity at around 60-100.?? if I put a 1500 watt heat lamp inside the hull will it damage the hull with intense heat close to the heat lamp?? is there any other way to force dry heat through the hulls?? does anybody have any idea how much?? weight i could lose? I will weigh the hulls as soon as I begin my "drydocking" and again when finished.. Thanks again all.

darrell

Ummm...yeah...even a 125W heat lamp is plenty to do a lot of damage. Visit my page where I cooked my hull

I did hear tale of a guy who mounted his Nacra 6.0 hulls upside down and inclined, built a tent around them, and using several different heaters, brought the temperature way up inside the tent for a day or so. I don't recall exactly what his progress was but I seem to recall he lost something like 8lbs per hull.

Do not get a heat lamp anywhere near your boat. I made the same mistake on a repair I was doing and totally cooked my hull and warped it.

I've seen Sunfish gain over 100lbs from water absorbsion.

Here is a way to dry it out safely.

Buy a long length of plastic flexible dryer hose. Put the dryer hose in the port hole. Dont tape it in just put it in loosely. Also remove your drainplugs or any other ports that you have. Now put a hair dryer set on low on the other side of the flexible hose. Again don't tape it in. Now just leave it like this for a couple of days and your hull will dry out.

Check your temp. in your hulls every hour or so to get the temp right. It should be just warm but not hot.

Mike Hill
www.stlouiscats.com

You can tent your boat in plastic and leave a humidifer running under the tent. I've done that with green wood and it dries it out nicely. The same would work with your boat if you left the port covers off. Its a kinder, gentler way of drying out the boat.

I'd be careful of pumping heat into your boat without a thermocouple and a thermostat on the heat source. You could cause a fire if you left it unattended overnight. Heat lamps, hair dryers, electic heaters can all get hot enough to delam your hull. I wouldnt risk it a thermostat to turn off the heat source.

If you want to weigh your boat take the car, trailor and boat to the local dump, they have a drive on scale, give the attendant a couple bucks and he'll weigh you. Take the boat off and repeat. Subtract total from boat less weight and you have your boat weight.

Bill

Keep it simple. If you open the inspection ports and take out the drain plugs, I think you'll be surprised at how quickly the boat dries out, even after just a week.

If the boat is exposed to the sun and no rain is allowed inside, they dry very quickly.

If you keep the boat inside this is true. However when I keep my cat outside water condenses in the hull. I can empty out my hull before leaving the prior week and the following week I always get another cup or two of water out of my hull.

This is part of the problem with leaving boats out. The water is constantly condensing and evaporating inside the hull. This is what causes the hulls to eventually delaminate.

Mike Hill
www.stlouiscats.com

Living in Florida, I probably have an even worse problem.

To combat condensation, I leave the ports open, remove the drain plug and elevate the bow. No water accumulation.

Hang a wet towel in the sun, how long does it take to dry?