Water trapped under deck - help

[CC Chuck]

I have a 1991 Ski Nautique that we have owned for about 15 years. I has about 2200 hours. This past summer I was replacing the vent hose on the starboard side of the motor and connecting it to the elbow that goes through the stringer just below and behind the engine and noticed that there was water in this elbow. I vacuumed out more water than I would have expected in a pipe that I thought ran under the deck to the vent in the center of the back of the boat. Then I started thinking that maybe there was not pipe that ran under the deck, but simply a cavity created by the stringer, floor deck and hull of the boat. I drilled a 1/4" hole in the bottom of elbow and allowed the water to drain out into the center of the hull to be able to be pumped out with the bilge pump. I was thinking of making an access hole in the deck floor under the back seat to view and pump out this area. First I drilled a 1" hole to determine what was below the deck. I encountered foam at the bottom of which was about 1/4" of water. I suspected that water was washing into the vent in the center back of the boat when the boat was quickly stopped and put in reverse. Then it was trapped in this pipe or cavity.

Questions from a new member:
1) how does vented air get from this elbow to the vent that is behind the gas tank? Is there a pipe under the deck?
2) does it make any sense to continue with my idea of making an access hole behind the seat and pumping or absorbing trapped water from there each time I use the boat?
3) Am I thinking right that water could be trapped in this pipe or cavity after coming in this vent?

Any comments or advice would be greatly appreciated.

[NautiqueJeff]

There could be water in the vent, but I wouldn't worry too much about that.

Your bigger issue is the water-soaked foam under your floor. Since your boat is a 1991, you have wooden stringers. Not only is that water-soaked foam adding lots of weight to a boat that is supposed to be light-weight, but that wet foam is slowly rotting your wooden stringers and floor, which will lead to big issues down the road.

The proper fix is a major undertaking. It involves floor removal, foam removal, possible stringer replacement if they are already bad, and application of closed-cell foam that will not absorb water, new floor, carpet, etc.

[CC Chuck]

Thanks much for your quick reply, NautiqueJeff. Your prescribed "major undertaking" is something that is not a surprising response, all be it unwelcome. Not sure I'm ready for our up to that just yet. Do you know if it is a solid pipe or "dryer type" hose that runs under the deck? The last couple of years we've started to do more surfing. The boat is loaded with weights and extra people in the back more often than when we were just skiing. Occasionally, if you stopped the boat suddenly a wave would wash into the back vent or over the transom. Before I got the water out of the vent pipe, I think it was so full of water that no vent air could be blown through it. So I'm making a practice of not abusing it with some of those harmful practices of extra weight and stopping suddenly. As a stop-gap measure, what do you think of installing a couple access holes under the back seat similar to the one for the packing access behind the motor? I could remove the foam in this ~5" hole down to the hull and, since the boat is slightly tipped to aft when it is on the lift, I could see how much water is in these inaccessable cavities and vac out the water as it drains from the foam. Hopefully I will not be soaking the foam as badly as we have been with abusive surfing practices.

[NautiqueJeff]

In the later 90's boats, there is a solid pipe. I assume it is the same for the earlier boats, but I am not sure.

I think you could add the holes you're thinking of, but I am not sure how much water you'll be able to get with them. Once the old foam is saturated, it doesn't really dry out or drain. You might get some of it though.

[CC Chuck]

Thanks much N-Jeff, I really appreciate your responses.

[bturner]

This is what typically kills off a lot of boats, not just ski boats. I've seen cruisers, off shores and runabouts all suffer the same fate of the dreaded rotted stringers. When these do get repaired it's typically from a labor of love and not a monetary thing. Money wise unless you're doing it yourself this can be an expensive undertaking. If you're doing it yourself it can be quite the project and one many rarely tackle again. I did one that that was enough for me.

[Jonny Quest]

A ski buddy has a 1984 Ski Nautique. He needs floor and stringers replaced. A local fiberglass shop quoted $5,000 for the job. I think that’s a fair price considering the work. However, that price does not include R and R of the engine and transmission. Ouch.

JQ

[bturner]

Prices I've seen up here are in the $7K to $10K all in (R&R, carpet, materials, alignment, etc.) depending on the boat and the number of "while you're in there" items like a dripless packing box but that's been years ago. I have no clue what we'd be talking in covid money or the time it would take. It is without a doubt an intensive procedure and not for the faint of heart.

[CC Chuck]

Thanks, you guys, for all the responses. You're not exactly brightening my day, but its pretty much of what I expected. As I said, unless there is a down side that I am not considering, I think I will install some access hatches under the back seat that seal as well as possible - ones with covers that turn onto a bit of a gasket or O ring. I will be able to at least get a bit of an idea of how much water is laying in there and will be able to vac it out - at least locally.

Prices of the newer boats with lots of bling make the idea of keeping these older beauties running a little more attractive - especially if one is willing to take on seemingly impractical repair projects on his own.

[Jonny Quest]

Or…..pick up a 1993+ year Ski Nautique. 1993 is the year when Correct Craft went to all-composite construction. No more rotten stringers.

JQ

[CC Chuck]

Yep, JQ, I found that out after I got my '91 15 years ago. Anyway, I got a good 15 years out of it and, really, it is still going strong.

[wayoutthere]

15 years and 2200 hours she served you well, and is still serving right ? Run it till she won't hold alignment then you can make up your mind about a rebuild or starting over.

how about some pics that make it obvious where in the boat you want to drill, and from left/right, pictures that show the whole plan your thinking that will help mitigate this issue. throw an object like a tape measure or pop can in there to give perspective.

i don't know the stringer layout, so pics of the problem and of your plan may get you some out of the box ideas and/or options

[CC Chuck]

OK, wot, I will snap some photos. Thanks for your interest, but it won't be till at least next week, we have guests staying with us for a couple of weeks.

[CC Chuck]

I cut two 6" diameter holes in the floor. These holes land between the two main stringers. On the starboard side I cut through the engine vent pipe, which runs between these stringers. It, in fact, is the dryer vent type pipe on my '91, NautiqueJeff (just an FYI). This pipe is totally surrounded by the expanded foam. On the starboard side, the floor deck wood was soaked, and when I removed the foam in this 6" hole down to the hull, I found it was quite wet and there was water laying on the bottom (hull). I tipped the boat back and absorbed the water out with a sponge. I left the sponge in the hole and allowed it to soak up as much water as it could. Water kept running slowly back to this access hole that I made. I squeezed the water out every eight hours or so and replaced the sponge each time. After about a week, I'm not getting any more water to drain to this hole, but I know things are wet where I can't get at. I know it's not perfect, but I think I improved the situation. BTW, on the port side, the deck wood and foam seems to be completely dry.
Here's a few photos, wayoutthere




The left hole is the starboard side (wet) Right hole is port (dry at least where the hole is)
These 6" diameter holes just fit between the edges of the stringers.


Hole on starboard side (partially cut). Note "dryer" vent type pipe.