17' Valco Bayrunner leak problem

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silverstreak1
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Joined: Tue Jan 11, 2022 10:26 pm
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17' Valco Bayrunner leak problem

#1

Post by silverstreak1 »

Hi Forum members,
I have a 1990 vintage 17' Valco Bayrunner I purchased about 8 years ago. It is powered by a 2004 Mercury 60 hp 4 stroke engine. After I got it I removed the motor, raised the transom cut out to be level across the back, and installed an engineered engine bracket and reinstalled the motor. Since I occasionally use it out in the ocean, I just feel safer and not as worried about taking a wave over my transom and swamping me. Then I removed the step up at the rear, removed the fuel tank, had a custom tank made that's now mounted in the bow area, and holds about 25 gallons of gas. Me being an older person, I didn't want to be worried about tripping on the rear raised deck. I then removed the 18" center console and replaced it with a custom made 36" center console with a windshield. It's a great fishing boat and thoroughly enjoy it. The problem I'm having is there is a leak somewhere and I can't seem to find it. I was out fishing in San Francisco Bay, it was flat calm, I turned on the bilge pump and it must have pumped out 15-20 gallons of water before shutting off. We were anchor fishing, and fished for another hour without turning the bilge on again, then quit fishing and ran about 15 minutes to the launch ramp. I loaded the boat on the trailer, pulled it out of the water and pulled the drain plug. It must have had another 15-20 gallons of water. A couple of months ago I crawled under the boat and inspected it. Both my transducers are mounted on a bracket, the bracket is welded to the transom, so there's no holes in the transom. I saw a questionable gap on each side of the bottom rail, so I used a silicon primer and siliconed the gap on each side. A few days later I raised the bow of the boat up so when I put a garden hose in the boat, the water would gather at the rear, and if there was a leak, it would be noticable. I found a couple of small leaks, primed and siliconed them in. Then when I go out fishing today, I get all the water i've described. I'm going to raise the transom end of the boat tomorrow to see if I can find a leak at the front.
I really like this boat and want to fix this problem. If anyone has any ideas, please let me know. Is it possible to replace the full length bottom keel? If so, who might do this? Or, is there someone out there that would troubleshoot something like this? I live in Morgan Hill, which is in Northern California. Thanks in advance.
Chaps
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Re: 17' Valco Bayrunner leak problem

#2

Post by Chaps »

Without physically inspecting the boat anyone including myself would be guessing as to where all your issues are but suffice to say that a 30 year old aluminum thin hulled boat is likely suffering from multiple age, stress and corrosion related problems (just like us!). The old saying a "death from a thousand cuts" oftentimes comes into play. You are on the right track, fill it to the waterline while it is sitting on the trailer and you'll soon find all the leaks. Best to fix them from the inside (pull up the floorboards) using an epoxy patching compound.
1987 24' LaConner pilothouse workboat, 225 Suzuki
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kmorin
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Re: 17' Valco Bayrunner leak problem

#3

Post by kmorin »

silverstreak1,
I agree with Chaps, those older, mainly riveted, hull seams have seen a lot of flex in their life. So leak testing may help you find and patch locations where the hull isn't tight any longer. One thing that is kind or hard to overcome in that type of test- is to locate the exact spot where the hull seams are leaking. Water can and will run along the edges of a hull seam to a low point before dropping off the hull- unless there is sufficient flow in the leak to make an actual obvious stream. Slow dripping leaks may show up as droplets leaving the hull 2' from the source!

Just a note when testing.

Also, the long seams on most riveted hulls have some or another 'rubber' or originally flexible elastomeric strip that was compressed into the seams by the clamping force of the rivets. These sealing strips do become brittle over time. I have seen several older boats' seams really "open up" after they were heavily loaded for one or two trips late in their useful lives.

I was asked to try to 'seal up' some of those seams on a Lund and tried for three or four attempts until the boat was given up as scrap- I was sealing the chine in 1' and 18" lengths but just chased "the problem" along. That seal strip was brittle and crumbled out of the chine as the boat was run in a small chop- after welding. So I'm just noting that there is a finite life to a riveted boat's various design features that might be important for your future maintenance planning?

cheers,
Kevin Morin
Kenai, AK
Last edited by kmorin on Thu Jan 13, 2022 3:10 pm, edited 1 time in total.
Reason: Typo's
kmorin
silverstreak1
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Joined: Tue Jan 11, 2022 10:26 pm
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Re: 17' Valco Bayrunner leak problem

#4

Post by silverstreak1 »

My Valco boat is not a riveted boat, it's completely welded. I have heard of a newer paint that is really thick and has been used as bottom paint on aluminum boats that have been prepared properly. This paint is very expensive but does work for stopping leaks. It is applied on the outside, but as mentioned before, the secret is to prep the surface properly. If the boat is already painted, the old paint has to be removed and the bare metal has to be sanded with 100 grit sandpaper, then use a recommended prep before applying 2 coats of this thick paint. anybody have any experience with this?
kmorin
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Re: 17' Valco Bayrunner leak problem

#5

Post by kmorin »

silverstreak1,
that is good news for your leak problems that your boat is welded. I looked up the Valco and found most of them (details not all that great online) have a chine that is an 'inside V' insert type of extrusion and as near as I can see? (again, online images not great) the welds are exclusively on the inside.

This implies the chine extrusion isn't welded outside? There are no welds I can see in the images- which are a little pixelated as you get zoomed in to the level of detail needed- so that implies this source of leak could be from 'flexure' over time, or from interior deterioration due to the socket in the extrusion being a source of crevice corrosion.

The good news is; if there are leaks in the chine extrusions? The entire chine could be 'glued closed' with an elastomeric/flexible sealant, like 5200, not a rigid epoxy type, from the outside; and would work to seal the chine for some period of time? To do this you might sand a narrow path along the chine's four 'edge's outside using 120-150 paper folded into a simple V and then inserted into the un-welded shoulders of the extrusion and the bottom or the extrusion and the topsides.

Then cleaning with acetone and applying the calk into what is very nice natural V grooved seam- you'd be able to get a very nicely attractive bead of calk and seal the seam from the outside.

Not being exactly clear about your transom modifications? I'd note that filling in the 'cut down' portion of the transom and adding
silverstreak1 wrote: Wed Jan 12, 2022 1:09 pm and installed an engineered engine bracket and reinstalled the motor
this could work to increase the transom bending moment aft. That is the lever arm of the outboard's clamp to the transom could be increased a great deal and that means the transom's joint to the hull all around its perimeter might be seeing a load that is not being supported? Couple that with your removal of the 'step' or tank bracket- which might have been a transom stiffener? You may have begun to flex the welds of the transom to topsides or bottom joint beyond their original design loads?

So by pulling the deck and looking at the welds under the waterline or if there are welds in the transom near the engine mounts? Looking to see if there are cracks there due to removing the 'step' which might have been a reinforcing xverse element in the transom frame? If these don't leak when you fill her to the waterline? You could also perform a simple 'impact torque test'.

Simply lower the outboard leg and the push hard (foot on anti-cav plate would work) with your foot on the lower leg. IF THE ENGINE moves- then look to see if the movement is in the mount? OR is the transom 'flexing'? If you have some help? have someone else do the leg push and simply sight along the transom's top edge for any flexure. If you can see ANY movement: the structure is inadequately reinforced and could therefore be subject to flex-to-failure of the welds and that would show up initially as leaks somewhere in the transom to hull seam.

Next, if you've replace the console- is the skiff framed longitudinally or transversely? If you have longitudinal stringers, and your new wider (heavier?) console is attached to longitudinal stringers (I can't find online a picture of the open bilge of this brand skiff) then a new heavier console probably isn't able to cause flexure or fatigue of the long wise welds to the hull? (leak points)

However, if the primary framing for your added in console is xverse frames? and they're stitched to the roll formed bottom panels? THen there is potential for those transverse welds to have been leveraged much greater than was originally designed. A wider, heavier, (taller?) console could provide a great moment arm on the xverse welds.

Since the hull panels were roll formed (or pressed?) that implies the alloy is somewhat malleable and not as rigid as say 5086? I'll assume 5052 but can't really confirm. What we can confirm by the images online is the bottom and topside were roll formed into a series of 'U'-s to provide panel stiffness and that implies there is an area at the two edges of each rolled 'longeron' that is strain hardened to give the panel as much flexure stiffness as possible for the scantling used.

So, another area to look for leaks is along the stitch welds of the xverse frames under the new console as those HAZ around the welds nearest the strain hardened areas of the bottom's rolled-in longs would be kind of sensitive to flex over long periods of time. So a larger console might have increased the loading of those frames' welds to the hulls. Again, initial failure would show up as small cracks around the ends of the welds or at the toe of the fillets at the hull panel's intersection.

If the leaks are found along the chine- sanding the shoulders followed by an etchant, followed by rinse and then sealed with flexible sealant will probably solve those leaks? IF the transom was inadvertently over-loaded by design mod's? That could be stiffened and resolved by welding in some additional reinforcement and if the console has induced some over-loading of the frame to hull welds? those too could re-welded and stiffened.

If the leaks end up coming from some sort of bilge corrosion? Then you'd likely resort to an area wide paint and coating type of sealant to solve the problem. Almost anyway you look at this its most advisable to strip the decking out, so you can see the bare hull inside and have access to any of the leak sources that you find.

I have no experience with exterior hull paints to stop leaks so can't report or advise. But if the boat is welded, very small welds could be used to seal up cracks- and then those cracks can be used to diagnose the weaknesses and reinforcement could be added to overcome the failures discovered.

Cheers,
Kevin Morin
Kenai, AK
kmorin
silverstreak1
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Joined: Tue Jan 11, 2022 10:26 pm
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Re: 17' Valco Bayrunner leak problem

#6

Post by silverstreak1 »

Hi Kevin,
Thanks for the in depth analysis, I understand what you're saying. I probably didn't make myself very clear, but all the work that was done was done by professionals that are in the business of doing boat repairs. The only thing I did was remove the raised deck in the back and the gas tank. The raised deck was not attached to the transom. What my mechanic did with the transom actually strengthened it, because he knew adding a bracket onto the transom that protrudes 18" would move the weight of the 60 hp 4 stroke out and put additional strain on the transom, so he reinforced it in order not to have a problem. before we added a larger center console we removed all decking and added reinforcement to accomodate a larger center console. At the time we did this we noted below the deck is full of foam, so it was impossible to check for cracks, or would be very difficult to try caulking any cracks. I am familiar with elastomeric caulk and think that's a great product to use along the chine. I really do feel that's where most of my problems are.
Thanks for your advice.
kmorin
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Re: 17' Valco Bayrunner leak problem

#7

Post by kmorin »

silverstreak1,
I'd vote the primary problem was from the foam in the bilges? If you search a little in the recent posts we've seen several photographic examples of the results of poured in foam holding thin films of water in the bilge against hull metal, for long periods. The bilge water, if allowed to stand in a thin film, shifts ph when it loses its oxygen, initially to the aluminum to form more oxide, and that shift turns the bilge water to enough of an acid to start a crevice corrosion cycle under the foam.
viewtopic.php?f=3&t=6486

Some earlier chemical makeups of phenolic acid foams would break down and were extremely aggressive corroding the entire bottom out of welded boats in our neighborhood in the 1980's. Since that time I've argued against foam in the bilges but given the under 20' LOA level flotation regulations its hard to find a cost effective solution? Cast polystyrene blocks that are then fitted into the framing is about the best solution I can think of using foam- but... the cost and labor value added to a small skiff would make that pretty pricey.

Taking out the foam is a very labor intensive process but that remains the sole method of insuring you can access the hull panels and bottoms of the pressed in 'longitudinals' where this type of hull building method has shown to contribute to extensive corrosion in the past.

Cheers,
Kevin Morin
Kenai, AK
kmorin
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