89 Sylvan Supersportster

Supersportster · Sep 16, 2009

Hey All,

I have had my first boat, 1989 Sylvan supersportser (aluminum), for just under two years.

This was my first full summer with the boat on the lake. The question I have is regarding a leak. I am planning on taking care of it this over the winter. I believe the majority of my problem is water coming in the seam between the back of the boat where the motor hangs on(transom?) and the flat metal thats immediatly on the inside of the boat.( can see in the picture). From reading here, I was planning on cleaning out old siclone out of the seam and filling with the Gluvit..

Also, my floors are in great shape, so I am unsure how to inspect the rivets to see if they are leaking?

Any advice/ plans to diagonos and repair are greatly appreciated!

Shane

ezmobee · Sep 17, 2009

Re: 89 Sylvan Supersportster

What I did with mine was stick a hose in the bilge while it was on the trailer and watch to see where the water came out. For me it immediately revealed a pretty serious pinhole leak.

Supersportster · Sep 17, 2009

Re: 89 Sylvan Supersportster

Thanks for the idea! I will have it in the driveway this weekend and try it out.

Once you found the leak, did you just use the Gluvit on the inside and outside to repair it?

ezmobee · Sep 17, 2009

Re: 89 Sylvan Supersportster

I slapped some JB weld marine on the leak and also on any questionable looking rivits.

Supersportster · Sep 23, 2009

Re: 89 Sylvan Supersportster

I now have the boat out of the water and with the garden hose have figured out that the water really really washes in between the transom and splashwell. It appears that the previous owner put some silcone there that is old and not working...(I will get a better picture then the one above)

I am just looking for any advice on my plan for action to take care of it...(good plan, or better ways to do it?)

I was going to clean and sand the area... then fill it with the marine tex Flexset, and then apply a good bead of the 5200 silicone..

As of right now, whenever water washes over to that splash well, by the time it drains back out, the bilge takes on ALOT of water. I want to get this sealed up 100% for the second full season with my boat...

thanks as always!

Shane

bigredinohio · Sep 23, 2009

Re: 89 Sylvan Supersportster

I'm not familiar with the make of your boat and I could be wrong but your transom looks very small/low as if someone cut some bad out of the transom, added a new aluminum cover and rehung the motor?

How much of the lower end unit and/or shaft of the motor sits in the water?

Rickairmedic · Sep 23, 2009

Re: 89 Sylvan Supersportster

Shane Red has a good point I hadnt noticed it before but it does look like possibly your transom and splashwell have been lowered . The upper part of my Splashwell and every other Starcraft outboard Splashwell I have seen is level with the gunwales . Looks like somebody wanted to put a shortshaft outboard on yours maybe they got a good deal on it and cut things down to fit ?

Rick

Rickairmedic · Sep 23, 2009

Re: 89 Sylvan Supersportster

Shane if I recall correctly your boat is also 16' heres a look at my transom to show the differances.

Rick

Supersportster · Sep 23, 2009

Re: 89 Sylvan Supersportster

The boats a 1989 Sylvan Supersportster, 17'9 feet. As far as I know thats how the boat came...but I have also wondered why its so low...

Everything seems to be orginal on the boat so I dont think it has been modified...I have seen a few others on forsale ads that looked the same...

But you can see my concern with the splashwell/transom leaking...

I am curious now, I will look for some other for comparison...

Shane

Supersportster · Sep 23, 2009

Re: 89 Sylvan Supersportster

I found this...Its a 1997 model, but appears to be the same...

bigredinohio · Sep 23, 2009

Re: 89 Sylvan Supersportster

Is there any way to snap and post a picture of your boat at the same angle? I only curious to see.

Supersportster · Sep 24, 2009

Re: 89 Sylvan Supersportster

Sure, the boat is out of the lake, but at my cottage, I am going to get it on the weekend. And I will take a picture of where I need to seal up between the splash well and transom.

SHane

Supersportster · Oct 1, 2009

Re: 89 Sylvan Supersportster

Ok Update:

Since I first posted this/started looking into my leak, I figured out it was mainly coming from where the splashwell meets the transom. I cut out some of the old silicone that was there, and took a picture of how BAD it is.

Any suggestions on fixing this? Should I get some of the marine tex flexset and fill it with that, or should I get it welded?

Second, I got some pictures of the keel...I am not sure what ot make of them. The rivets seem to be tight, but there is a very small gap at some parts.

Is this anything to be worried about?

Thanks

Shane

ezmobee · Oct 2, 2009

Re: 89 Sylvan Supersportster

3M 5200 will seal up your splash well leak. That's what I'd use. I wouldn't worry about the keel. Mine looks the same in spots. I may be wrong, but I think that whole piece is basically an appendage and does not need to be water tight.

Supersportster · Oct 2, 2009

Re: 89 Sylvan Supersportster

Exmobee, Thanks! I am thinking the same thing about the keel, but I am still fairly new to boating.

Intially I was thinking the 5200 to seal it up. But I am worried that area flexs some when I gun the motor. Does 5200 flex abit when its dry?

ezmobee · Oct 2, 2009

Re: 89 Sylvan Supersportster

Yeah I think it flexes a little bit. I got an idea, have someone lay the bead of 5200 in the crack WHILE you're gunning the motor! There ya go, problem solved! LOL, or not

Supersportster · Oct 2, 2009

Re: 89 Sylvan Supersportster

LOL I'll supply the whiskey for them before we try it! LOL

I have been looking at this stuff.. http://www.marinetex.com/marinetexflexset.html

It seems like it will work for what I need, then for over kill i will put the 5200 on top when its dry...

Shane

Huron Angler · Oct 2, 2009

Re: 89 Sylvan Supersportster

Nice Slyvan

I've seen quite a few of those around and they all have that shallow transom...since the splash well is rather large they make them that way, justlets water in when decelerating abruptly after running on plane.

As long as you are sealing those leaks the water will drain right out of the splashwell no problem. Let's see some more pics

fire7882 · Oct 2, 2009

Re: 89 Sylvan Supersportster

Personally. I would only use one type of sealant. Putting one on top of another won't be of any benefit, look worse, and aggravating to narrow down which one was the cause of any future failures.

I'd clean everything real well and use the 3M 5200. If it doesn't work for some reason, then I'd try something else.

fire7882 · Oct 2, 2009

Re: 89 Sylvan Supersportster

3M 5200 Data

The above data from 3M describes 5200 as "Tough/flexible polyurethane polymer"

89 Sylvan Supersportster

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