leaking hulls

So, i'm back again, i think boat ownership must be like car ownership... you always beat the cr*p out of your first one. anyway, i have a leak in my port hull. i found a crack on the underside of the hull and filled it with epoxy and it seemed to have lessened the leak by about 50%. however, there seems to be another spot leaking. when i pull the boat out of the water i hear a hissing (air sucking in) around the area of the front bar. has anyone had this same problem? the previous owner said he had some cracks develop there so he went in and reinforced the area. if the cracks have widened (even though i haven't been able to find them) how would i fix them. do i need to remove the bar and put epoxy/rubber cement in there? also should i do a 'soap bubble test' in order to find any other leaks. i would say that the leak is in the order of a gallon an hour so not huge but annoying and performance affecting.

if you have had experience with this or know a good way to fix this PLEASE let me know,

happy sailing,

justin in hawaii

First, you hve to find out EXACTLY where it is leaking from. Sounds tough, but I always fill up the hull with water and see where it leaks, then fix it. You will need help as it turns very heavy when filled. This is however the best and surest way to know. We did a Hobie 17 sport this way once and found a big leak in the daggerboard well.

I would not fill it with water! That is not a sound way to find a leak. Get a hair dryer and some dishwashing soap. Soap the hull up and blow air into the drain hole with the hair dryer. The leaks will bubble. There are breather holes under the front x-bar that most likely make the sound you describe. Likely leaks are under the lip at x-bars, dagger wells, under the lip at the nose and the ports. Once you find the leaks you can then decide how to repair them.

What´s the problem with filling with water ? I´d like to know. If you vent air dry the inside of the hull afterwards. All the mat and woven cloth inside are saturated with fiberglass resin long ago cured what could go wrong ? Also it is not necessary to FILL it with water.

By blowing air into the hull you will somehow pressurize it and that could be dangerous. Aircraft fuselages have to be built strong to withstand the pressurization that force it to expand outward, you would be doing exactly this by blowing air into the hull.

is the hull filling with water bad for it too? what steps can i take to clean it/dry it out to avoid any damage?

My first response would be that it is best to keep water out of the hulls. My second would be that the hull is not designed to hold water and I would think the weight of the water against the inside of the hulls will do far more harm than the pressure of a hair dryer. Now, if you put pressurized air to the hulls you can blow them out but a hair dryer does not produce that much air flow. I've put as much as 20lbs of compressed air in a hull by modifying a plug, but I wouldn't recommend that to anyone.

I still say a hair dryer and some sudsy water will do the trick and the boat gets washed to boot!

Here's a couple reasons...

Unless you have access to a fire hydrant, it'll take forever. If the cracks are at or near the top of the hull, there's a good chance the water won't come out. And last and foremost, it'll weigh a ton (actually probably several tons). You'll be putting some seriously high loads on the boat that the hull was never designed for, so there's probably a pretty good chance you'll break the boat.

A much better method is to pressurize the hull with air through the drain plugs (you can actually use a piece of rubber hose and blow it up with your lungs). Then squirt soapy water on the hull and look for bubbles.

If your hull has cracks through the fiberglass, the proper way to repair them is by reinforcing the cracked area with fiberglass cloth and resin. If you just put epoxy or caulk into the crack, it'll probably just continue to spread and could eventually lead to hull failure.

sm

Well guys, the plot thickens! After reading your responses I went to my boat (parked on lanikai beach) and put it up on two saw horses. What I saw was horrifying (for me). Extending from the area of the dagger board, but not quite at the 'pocket' is a crack about a foot long traveling forward. I had seen it before but it looked much smaller, almost a hairline, so I filled it with epoxy and figured I was done. From what I can tell and from what I can see the crack doesn't go right through the hull but when I touched it residual water in the hulls came gushing out. I will upload pictures, if I can, but I think I am gonna get a pro in to fix this one. Before he comes tho is a fix like this possible? Luckily the crack is right above the inspection port so it's reachable.

Justin in Hawaii

I guess I should not have mentioned the word FILL, it is not necessary. I have done it many times and found cracks and nothing happened. One time, my crew decided to ferry my H16 across the lake and forgot to put the plugs in place, both hulls filled with water and we had to drain them out. Nothing happened to the boat. Your method sounds good but sometimes it is difficult to pick up the bubbles, I prefer to put some water in than blow air into the hulls with a device.

Water weighs about 8 pounds a gallon. A 55 gallon drum would weigh 440 pounds. A ton is 2000 pounds, 2200 pounds if you go metric. With less than a drum of water you can move the hull sideways, turn it upside down, roll it, and see where the water comes out. The hull will not weigh "several tons".

ok need to clarify something. so hulls have a foam sandwich design right? if this crack goes through the foam sandwich but not through the internal fiberglass layer can i just grind out the external layer and relay glass or do i have to somehow inject the foam too? the crack is right at the bottom of the hull (where it slides over the sand) and it seems that just glass would do the trick as its not a large area. any pearls of wisdom?

one more qs. the very bottom of the hulls look thin (i can see light through them. does this mean that this part does not have the foam sandwich between layers of glass? if not his repair will be easier. also, should i gel coat after to make the hulls thicker?

Justin, I posed a similar question a couple of weeks ago here: viewtopic.php?f=13&t=15708

Also, if it turns out you need to do a bottom job, go to page 12 of this link: http://www.hobiecat.com/hobieclass/eHCA ... 0_2008.pdf

Good luck!

The H18 is solid glass on the keels, or bottoms. There is no foam sandwich on the bottom. It is common to see the bottom appear lighter or opaque. If the crack is in the bottom it goes all the way thru, IMO. The inner glass seems more like a burlap bag to me so it not being broken would seem right even though the hull is cracked. You will need to grind out the crack in a "V" and then reglass. You are lucky the crack is where it is. You should most likely do a complete glass job on the keels. Since yours is a beach boat and not raced I would suggest putting some extra glass on the keels and gelcoat so you only have to do this repair every other season or so. My beach boats need reglassing every 2 years if I sail regularly.

It's a pretty easy repair if you're half way decent at working with your hands.

As was already said, there is no foam sandwich on the bottom of the hulls, only solid fiberglass. You basically want to grind/sand away most of the fiberglass about 2 to 3" on either side of the crack so that it tapers down along the length of the crack. Then you can layer glass into the "V" that you ground away to rebuild the damaged area. Once the glass has cured, you can fair the repair in with the existing glass (by sanding). If you're really concerned about cosmetics, you can spray on gelcoat to match the existing hull color. Since the crack is right below the porthole opening, you can also add several layers of extra reinforcement inside the hull to make the repair even stronger than original.

Just make sure you prep the repair surfaces really well by sanding and throughly cleaning with acetone or rubbing alcohol to insure that you get a good bond.

sm

Rather than soapy water to find leaks, I use kid's bubble blowing fluid. The dollar store had a 1/2 gallon jug of it. It make 'stronger' bubbles. If you have a big hole, sometimes soapy water just blows out of the way; Not enough surface tension to span the gap.
I use a leaf blower in an open porthole; Leave the drain plugs open! It doesn't take much pressure to 'make bubbles'; If you don't vent/limit pressure, the hole(s) you find will be the ones you just made with the blower.