Starting at the BEGINNING


Active Member
Pressure washer works best but you need to be careful. I used a electric pressure washer
that's not strong enough to do any damage. A gas washer can cut the boat in half, in fact
I splintered a hole in a 2x6 using one.

As long as you can remove the splash guard working with the boat on the trailer seems to present
no problems.

Takes about 4 month after cutting holes to get the boat dried out enough to do fiberglass work. I
kind of pushed faster on the one I'm completing now. I started in the spring and am mostly done,
smashed keel, broken bow and all that. I only worked on it on weekends so that's about how long
the hull takes. Probably another 2 months of winter weekends to make a rudder/centerboard from
scratch and find the parts on e-bay.
Thread starter #62
Hey guys, just wanted to give feedback on the leak test. I started the process by using some old packing tape I had lying around. In order to pump air into the hull, I used an old air matrice pump we had in the closet. It seemed to do a very nice job pushing air through the boat.

As you see above, I started by slowly taping off the stern inspection port (which was used to dry the hull).

The above pic shows the stern inspection port sealed off with the matrice pump in place.

Above is a close up in case you wanted a better look.

Above, you can see that there is another inspection port near the splashguard. With the pump on, and the forward inspection port open, there was not enough air pressure in the hull to to force air through the vent hole in the forward wall of the cockpit. I sprayed a mixture of water and dish soap on vent hole to look for any bubbles. No luck.

So above, it made sense to start covering up the forward inspection port one strip of tape at a time. Knowing, from our member's guidance, that too much air being forced into the hull can cause major damage to the boat, I was very careful here. Each time I put on a strip of tape to cover that splashguard inspection port, I would leak test the vent hole in the cockpit. My thoughts were if air pressure was enough to make it push out that vent hole, there should be sufficient pressure for air to push out any holes that may exist in the hull, or around any fixtures attached to the boat. The forward inspection port was almost completely covered before enough air pressure was available for the test. (Just anout 1/2 a strip's with of tape was left open on that forward inspection port).

Above you can see how much of the forward inspection port was taped off in order to get enough air pressure to leak test the air vent in the forward cockpit wall.

Once I could see bubbles forming around the air vent, I knew I was ready to leak test the entire boat. I used a solution of water and dishwashing liquid soap and put it in a spray bottle (as was suggested by our members). I then set forth to spray down every inch of the boat, paying special attention to any nicks, cuts, scrapes, trim, rivets, screws, or fixtures on the boat that could be causing a leak. I did this process TWICE........... And could not find any bubbles (except for the vent hole.

My questions are:
1). Does this process look right to you all? No leaks, right?
2). Im thinking that my next step is to fare over the big gouges in her hull. Does this seem like the next step to be taken?

Cheers to you all,

beldar boathead

Well-Known Member
I think you should have taped over the vent hole. That left a path of least resistance for air to escape the hull. Since that hole is hopefully larger than the hole in the hull, the air would choose to escape from there rather than work its way out in a meaningful way from a small crack or fissure.
Well... the mattress pump is a pretty low volume pump and low pressure. But I'd be careful completely closing the forward port anyway.

It sounds like you did a pretty good leak check. Getting bubbles at a known leak location and no bubbles anywhere else sounds like a pass.


Upside down?
Staff member
Did you draw a bubble over the mast tube? The best way to do that is to partially tape the tube.
I mention this because the hull was very wet initially. The water must have entered somewhere...
Thread starter #66
Thanks guys....... you think I should do the test again? It only took 20-40 minutes to do the entire thing. I could easily tape up the air vent, leaving a bit of pressure to escape the forward inspection port. If you think that would give me a better gauge of this boat, Ill do it. Id hate to fare, sand and paint.....only to have to do it all over again later.

Wavedancer......... crap.....I forgot to do a leak test over the mast tube......... Lol......I did it over the daggerboard by mistake ....... My bad.......... So it may be prudent to re-do this test?

Fhhuber........thanks buddy. I hope you are right!

Let me know what you guys think.

Thaks for all the input guys.

Warm regards,
Beldar is correct you have several paths of least resistance for air to escape the hull. I would tape over all port holes, bottom of centerboard trunk and just blow a couple of lung fulls of air in the drain plug and tape over. You only need a slight pressure increase. You might have to replenish the air if you have a leak. I would soap the mast, centerboard, around the bailer, top and bottom and along the trim, top and bottom, along the splash rail. Work each area slowly with the soap. The suggestion of taping over part of the mast and centerboard is good as it would make drawing the soap over easier.


Well-Known Member
I have no experience :oops: in finding Sunfish leaks—using a pressure test, ;) anyway.

But, yeah, I'd try again. :(

Located where water pressure is the greatest while sailing, daggerboard-trunk leaks would be my first concern. The daggerboard is the first part of the Sunfish to find boulders! :eek:

But I would expect an "experienced" Sunfish to have enough "natural" leaks to permit greater- and longer-lasting- air pressures. How about placing a Tupperware bowl into each inspection port? If the pressure gets too high, they'll pop out.


Active Member
It all depends on how much air you're shoving into the fish. if you're using a powerful shopvac, you could leave a inspection port off and still create enough interjor pressure. A small little pump you could probably seal the entire hull up and not worry about "exploding" the hull. The idea is to create a slight difference enough to push a small amount of air out a crack. In a sealed small hull a compressor will do damage. A hair dryer would be about right
Thread starter #70
Hey guys,

Ive been thinking the last few days on what to do here. Im thinking this - having air squirt out the vent hole, probably negated the effectiveness of the leak test. So, I should probably redo it. No sweat.

The trouble is exactly how to do it now. Knowing that I am using a pump for an air matrice, do you think it can produce enough pressure to destroy the hull of a Sunfish? If the pump was powerful, it would destroy the air mattrice as well, right? Is an air matrice more structurally sound than a Sunfish?

Do you guys think I can seal up all the inspection ports and the vent hole in the cockpit, then turn on the matrice pump to presurize the hull? Its got to be less pressure than a hair dryer, right?

Gonna' need some perspective on this one.

Still thinking this one over,


Well-Known Member
If you have an aquarium air pump, that would probably be a safe bet. The air mattress pump may be too powerful. :oops:

Try the hair dryer with your soaped-up brush at a bow handle screw-removed. My guess is, you'll be spewing a fountain of air bubbles around your head! :confused:

But your dog might have a good time! :p


Active Member
Hey guys,

Ive been thinking the last few days on what to do here. Im thinking this - having air squirt out the vent hole, probably negated the effectiveness of the leak test. So, I should probably redo it. No sweat.

Like I mentioned above...air coming out a vent hole isn't a deal breaker. You just need to have a SLIGHTLY higher pressure internally and if air is coming out vent holes, no biggie. I was able to hook a powerful shopvac up to a transom drain, leave a cockpit inspection port open and STILL see I had a couple leaks up by the bow at the hull/deck joint. Air was POURING out the cockpit vent, but there was enough internal pressure to still do a leak test. Had I sealed up the vent, my shopvac probably would have exploded my little fish hull.
I do this kind of test A LOT on larger boats. I seal up the companionway and stick a large fan blowing down below decks. There are locker lids, etc that let out air for sure, but it provides enough internal pressure to spray soapy water over closed or sealed windows/ports, hardware and such, to see if anything is leaking. On even a larger scale, you do this with a house on the front door typically. That way you can go around your other doors, windows, etc and see if there is excessive leakage (for keeping AC in and Mr. Winter out!!!)
The Sunfish hull is SO small in comparison, that you can easily "overpower" it with something too strong.
Just start easy and you should have a sense on if you're putting too much internal pressure. Just don't be impatient and slam a 220V compressor into a "sealed hull" :-O A hair dryer might be a little bit on the "light" side, but the idea is to give a reference. Many ShopVacs can really put out the air, so you might be careful. A mattress pump may be somewhat less, but then again, it depends. Use good judgement.
Thread starter #76
Fair enough......... Moving along then.

Ordering the rudder and tiller today for the rudder conversion from one of the reputable sellers on this site. Also found that star spangled sail on ebay that I wanted ordering it today as well. .... Things are moving forward.

Now back to the project.

I would like to fare this noat up. Lots of small dings in the bottom and sides of the boat. Would like to smooth them out and then paint.

Ive read up a bunch on techniques, but nothing says success like experience.
Anyone have an easy and effective process to fare this boat and prepare for the paining process?

Thanks again for all the help,


Active Member
EVERCOAT Formula 27 Filler | West Marine
For filler. Skip the Bondo, without a doubt. If you're more experienced, West Systems with their selection of fillers is best for filling and then fairing. Expensive. I've used the Formula 27 for years with never a failure. It has its' limitations but for small nicks and gouges works fine.
Use a Primer before painting.
Use a higher quality paint, preferably one you can final buff in the end, if you're looking for top notch results.

Don't forget to leak test your mast tube and daggerboard slot. ;-)

beldar boathead

Well-Known Member
EVERCOAT Formula 27 Filler | West Marine
For filler. Skip the Bondo, without a doubt. If you're more experienced, West Systems with their selection of fillers is best for filling and then fairing. Expensive.
I've used West G-flex toughened epoxy with various West fillers with good results. I've not tried West Thickened g-flex with fillers. Advantage of g-flex is the squeeze bottles don't cost too much and are very easy to use.
Thread starter #80
I got a wild hair and had a few hours to kill, so I did the leak test again. This time, I taped over all the inspection ports and vent hole. I also taped over the mast tube and dagger board hole (leaving just a bit of space open to film over with bubble solution.) Using packing tape, an air matrice pump, and common sense, my thoughts were that the weak tape would lose its seal before the boat would pop.

Im glad I redid the test. Thanks to those of you who recomended it. I found a bunch of leaks - and one or two that have me concerned.

Here they are: (look for the bubbles or the circled markings onnthe boat)

Both blocks that hold the traveler

Next leak, moving around the boat from stern counter clock wise, checking all fixtures, dings, and trim, was the daggerboard hole below:

Then below, you can see the horn cleat, previously moved and sealed (not). (By the way, no backing board behind the new location). Those holes were the previous cleat was located, was never sealed so lots of air leaking out here.

Then there is a very small leak coming from the port drain plug, abeam the splashguard:

Two holes on the starbord side, where the side meets the bottom:

Then below, you see another leak where the side and the bottom meet, just abeam the cockpit (two feet stern of the above leak).

There are a few more leaks associated with the old rudeer system that I removed to facilitate the stern inspection port. But those should be easily fixed (much like horn cleat holes).

Ok, ill post the leak I am most concerned with later today. There is a rivet in the trim, on the starbord side near the bow,mthat is missing. Its leaking there. Ill post pics later today.

I've located the nearest West Marine in the DFW area - gearning up to buy the resin, hardner, and glass for these upcoming projects.

Thanks for all the advice guys - and thank you in advance for all the advice thats headed my way.

Warm regards,