Help - Some Questions on 1997 H-18SX Hulls

Hi

We inspected our hulls at night with bright lights after having estimated 3 or 4 gallons of water in each hull after a 4 hours of 20+ winds on Lake Michigan yesterday. We might get a gallon each before, under similar conditions. We haven't found the source of the leaks yet.

1. We saw no obvious fibreglass cracks/breaks. There are gelcoat surface chips and cracks in the daggerboard pockets. Can water penetrate through un-gelcoated fiberglass under high pressure?

2. The are 6' x 1' plastic bags in the hulls. One came out and does not hold air. Are these positive floatation bags or just something used in manufacturing the hulls to keep the foam block in place?

3. The top of the interior hulls are green, and the bottoms are yellow. Why?

4. Gelcoat has been sanded off the bottom of the hulls about 4' Again, can water penetrate the full fiberglass under high pressure from 18+ kts speeds?

We are going to pressure test with a leaf blower on Wednesday. Do you have any recommendations or scary stories to tell

Thanks in advance

Using a small shop vac, re-set the tube so that the vac blows instead of sucks. Then unscrew the porthole covers, place the end of the (blowing) tube onto the drain plug hole, and duct tape it loosely into place (or have an assistant hold it more or less in place.) Don't blow with too much pressure, in fact the less the better, as you can easily blow the seals etc. and make the problem worse rather than better.

Using a spray bottle, with a mixture of dishwashing soap and water, spray the following areas: Gudgeons, anchor plates (below the shrouds and below the front cross bars,) around all the cross bars, inside the daggerboard wells, and on the port hole covers. Spray generously and often.

Then start to cover the portholes, sufficient that there is positive airpressure in the hulls, and check each area for bubbles. 9 out of 10, you have a porthole leak. 3 out of 10, you might have a leak in the breather hole underneath the front cross bars. Anchor plates, especially if retrofitted are another source. Inside the daggerboard wells can be tricky, as you have to check top and bottom seams, and the top corners that get beaten up.

Wash off the soap, clean with acetone, and complete the fibreglass repairs and recaulking. Email me off line at lunnjohn at magma dot ca, and I'll send you pictures of soap bubbles. My repair worked great on port, starboard has to be re-done as I missed a spot.

_________________
2015 H16, with spin,
SOLD 1989 Hobie SX18 Sail # 1947 "In Theory..."
'Only two things are infinite, the universe, and human stupidity. But I'm not sure about the former.'

I found my leaks along the hull to deck seams. A large void was found in the daggerboard rope hole. The caulk can also go bad around the ports & drain plugs. Do not fill the vent hole, just make sure it goes thru to the inside of the hull. (Or drill out to 3/8" fill & re-drill to ensure your not water logging the foam). Other areas as John said are around the daggerboard wells.

The plastic bags in mine have foam in them. I know because I added 5" ports behind the rear crossbar. I now can reach the transom & crossbar area by sticking my arm in up to my elbow.

Good luck, my boat is now dry and it's a great relief

_________________
1989 Hobie 18 Worlds Boat, Magnum Wings & Spinnaker
1987 Hobie Holder 20 #273

dale.vanlopik"at"att"dot"net

Thanks to you both. The problem was the porthole rings and the breather tubes. We used the shop vac, and the top half of a plastic pop bottle.

The wide end of the bottle fit over the 2 and a half inch shop vac tube, and the small end fit inside the drain once the drain plug was removed. It put very good pressure into the hulls.

We plan to use marine sealant inside the hull and outside of the porthole rings. Also, we plus to seal along the front of the forward crossbar along about 5" at each end. Do you agree with that?

Outside of that, we could not detect any other leaks.

Again, thanks.

We have inherited some covers that appear to be like the ones in the Hobie catalog...silver and black. They are probably 10 years old, and didn't make it easy to use them last winter as they are torn.

My thoughts are to go with the Wal Mart tarps described above.

John, why not pull the portholes and reinstall them with a gasket and sealant? Just sealing around them will come off and they will leak again. Adding sealant to the front of the crossbar won't prevent water from entering the vent holes, I'd leave that alone.

I hope no one minds that I revive this four month old topic; I've got hull leaks and need a bit more assistance.

I leak-checked my 1998 18 today, and discovered that I have bubbles coming up around the front portholes and front crossbars on both hulls. The hulls themselves are solid; no stress cracks visible topside, and no softspots. I see from the below posts that regarding the front crossbar, the breather hole is the probable culprit. Tell me, I'm not quite sure where to find this hole to check/ fix it. Can someone point me in the right direction?

With that said, what would you suggest is the best way to address the crossbar leak? I assume the breather hole is there for a purpose and should remain patent. Tell me, maybe bubbles coming up around the crossbar are normal because of this breather hole? Hmm, is there a breather hole for the rear crossbar; no leaks there.

Regarding the porthole leak, I see the suggestion below to remove the portholes and then reinsert with a gasket. That sound like an ok idea, but I assume that the rivets would then be replaced with screws, yes? Wouldn't it be easier to simply caulk around the perimeter of the porthole on the inside of the hull with marine-grade Goop? I'm scared to death to drill out the rivets -- sounds like major surgery to me with potential for even greater problems!

Thanks for your thoughts.

Indy, re- read all of the posts. FYI; I had my boat in pieces (hulls off crossbeams) when I leak tested.

The breather hole is under the front crossbar. You will see bubbles around the front crossbar when leak testing. It is from the vent hole. There will be minimal water intrusion from the vent hole . Do not eliminate the vent hole. As I stated in another post, hulls need to have a vent to keep equal pressures due to expansion & contraction of the air in the hulls due to heat or cold. A hull that is totally sealed may exert enough pressure or vacuum to delaminate the glass foam sandwich of the hull & decks.

Depending on your port style, (if a pop in port I would replace, screw in I would check the O ring gasket & reuse) I would drill out the rivits and re-bed the port. Re-bed with a silicone caulk, do not use 3M 5200. Do not bolt the port flange down too tight as you may warp it and it will be difficult to screw the port on or off. (I need to re-bed my 5 in ports for that very reason). You can go to: thebeachcats.com and look up a port hole replacement tech help.

I can be reached offline at djandddale"at"charter"dot"net for further questions.

_________________
1989 Hobie 18 Worlds Boat, Magnum Wings & Spinnaker
1987 Hobie Holder 20 #273

dale.vanlopik"at"att"dot"net

In heavy winds or heavy loads, we get gallons of water, especially in the port hull. We have removed and replaced the complete 5" port rings, caps, and gasket material. We have sealed around the front crossbar. When we leak test with the shop vac and soap bubbles, we get a few air bubbles through the cap/threaded ring, but we don't believe that is sufficient to cause gallons to come in.

We have leak tested around the daggerboard pockets, grundgeons, drain plugs and along the edges where the deck meets the hulls. No indication of soap bubbles.

We're told that water can seep in where air doesn't blow out. Is the reasonable?

Again...the heavier the wind/load, the more the boat will take in. But there are no cracks below where the deck meets the hulls.

We're told to fill the hulls with water...and see where it leaks out from. Does that make sense to do?

Thanks for your thoughts. What should we expect leakage wise with heavy winds and/or heavy loads?

I would rig the boat, tighten the rigging and redo the leak test. How much movement do the hulls have in big waves? Do you have the anchor brackets at the beam mounts? I would spray down the entire hull, my leaks came from poor repairs made by the previous owner.


In the last year the consendation in the hulls would be my largest water issue due to only keeping the drain plugs open. I hope I fixed that by getting extra 5" covers and making a vent out of 1 1/2" PVC pipe. I'll check it out later this week when I get to the boat.

_________________
1989 Hobie 18 Worlds Boat, Magnum Wings & Spinnaker
1987 Hobie Holder 20 #273

dale.vanlopik"at"att"dot"net

Trying to drill out the port hull rivets (pop-in type) is almost impossible .... I just order new rings ... cut the old rings w/ a Dremel tool (using a Cut-Off wheel) on either side of the rivets and w/ a pair of "nipper" pliers cut the rivets ... much faster ... easier ... less fustration!!! Then I use 3M 5200 (!!!) w/ machine screws and seal those puppies down PERMENTLY. Frankly, I'm tired of re-sealing hull port rings every few years ... the rings haven't leaked since!!!!

Next time I just take out the screws ... take a razor blade cut around the porthull ring and w/ a putty knife remove the ring which I expect to break and install a new ring.

Spending an extra two hours to save a $15 part does not seem cost effective to me ... call me stupid ....

Just don't use TOO much 3M 5200 ... a thin bead is enough

_________________
HarryMurphey
H-18 mag/ #9458
Fleet 54 Div 11

I have been drilling out rivets for years, helping with experimental aircraft and in my business. I spent the day yesterday drilling out rivets and replacing fixtures in my 18 and had no trouble at all. For me the easiest way to remove rivets is to use a large diameter drill bit the size of the rivet head, or larger. I use very sharp drill bits, with VS drill on slow speed with light pressure. The idea is to take off enough of the rivet head material to make it very easy to remove the head, but not touch the fixture or surface below. I drill the head of the rivet down only a short distance, takes about 5-10 seconds with aluminum (a ltl bit longer in Stainless), just to weaken the head (once you get good at it you can even drill off the head completely and not touch the surface below), then I use a thin nose chisel and hammer to knock off the head (it almost comes off with hand pressure), then I use a punch to tap out the rivet body. When I do get a stubborn rivet body, or on a very delicate painted surface, after poping off the rivet head I'll use a drill bit the same size as the rivet body, or just a tad smaller to loosen it up, and pop it out. For me it works every time, on any rivet, and I've done thousands. Stainless/stainless aren't any harder to remove then Aluminum/aluminum.

The same proceedure works on flush or counter sink rivets, but the opperation is a bit more delicate in that I drill the entire head off, so bit selection is more important. If I encounter a rivet that spins before I get the head off, I use any thin flat blade between the fixture and mounting surface to wedge and add preasure to the rivet and fixture, which stops the rivet from spinning.

You have discribed the exact method that I use for removing rivets ... but my experience w/ the aluminum rivets used on the H18's has been completely different .... I have tended to work on 80's manufactured hulls. The rivets used then were aluminum w/ a STEEL shank in the middle that the steel shank could and often broke off at the same level as the alum rivet head. And it only takes one rivet like that to cause the drill bit to walk and you ruin the ring. ( I just checked my spare set of hulls in the yard .... 6 rivets/ring ... 3 of 12 rivets have protruding steel shanks ... one ring is cracked and has to be replaced anyway ... my quess is that the previous owner did not lubricate the O-Rings on the hull caps and there is no sealent of any kind glueing the ring to the deck)

Now you can take a small grinder and grind the steel shank down and then you can buy a new 1/2" Titanium Drill Bit for $23-$26 to use .... then there is the added cost factor of your time/labor... I can remove a ring in under 15 minutes now that I have the process down .... and there is always the "SPINNING RIVET" problem. It always took me an 45min or more doing it the "careful" way of removing the rivet heads and there was no guarantees of success ....

I've done it by removing the rivet head several times ... but it was a pain in tha a-s to save the $15 ring . I quess I just need more patience. So when I needed new "Hull Caps" I bought them w/ rings ... saved the rings for later... and use the brut force method when I finally re-sealed the rings to the deck when I got tired of re-sealing them every two years w/ silicone....

And since I started using 3M 5200 I haven't had to re-seal a hull port ring to the deck since ... Fix it once, and forget about it !!!! You just need to do it correctly the first (and only) time.

And I do currently have replacement rings in my spare parts box .... through it's starting to look like I won't ever need them ....

(hull caps slit but the rings can last forever as long as you use a little SAILKOTE/Silicone on the rubber seals on the cap and the ring is firmly attached to the deck at all points)

Both methods work ... its just a matter of patience and cost

_________________
HarryMurphey
H-18 mag/ #9458
Fleet 54 Div 11

I have removed thousands of aluminum rivets with steel mandrels. For my business we needed an aluminum rivet but with stronger mandrel breakoff for a tighter, or in our case, deeper set in solid rubber. I've not had trouble with steel mandrels sticking up walking the drill bit. Just tap it down, the button is at the other end. We very rarely have to use a drill on the rivet body at all, only the head gets worked on, the body is knocked out with a punch. if I was working at the wrong end of a rivet, which we have done, I would use surface trim plyers to cut off the body, then tap out the rivet. We avoid drills as much as possible.

Even once the head is drilled shallow before it comes off as a ring, its possible to tap out the rivet. The force of the tap pushes in the rivet and removes the head at the same time, but the head prevents the punch from slipping off. Hard to explain. Trick is knowing when to stop cutting down the head of the rivet, leaving just enough to hold the punch and still release when struck.
And as has been said the spinning rivet can be a pain. It can heat up so much you can burn through just about anything, making a very nasty big hole, or you will sit there forever doing nothing but spinning the rivet. We just slide a thin tapered (wedge shape) flat blade between the fixture and mounting surface, tap in until very tight, and the rivet spins no more. Sometimes you will get lucky and this will pop the rivet for you before you have to drill any more.

oh well, sorry, enough about freakin rivets.

As crazy and simple as it seems I never thought of using some punches and driving the steel mandrel down. If I can get to the underside of the rivet I have Needle-nose Visegrips that I clamp on to hold "spinning rivets"

I quess you are never to old to learn a new trick .... Thanks

I'll give that a try next time ... but I will need to replace my one "sharp" 1/2" Titanium Drill Bits instead of using my "dull" bit, as my co-workers/friends keep borrowing them and have ruined them both drilling into "drywall w/ metal studs" for wall mounts.

Got to run off to Annapolis MD now to hop onto a friend's 43'Trimaran for a race to "Baltimore's Inner Harbor" tomorrow and back to Annapolis on Sunday.

_________________
HarryMurphey
H-18 mag/ #9458
Fleet 54 Div 11