Flooding thru transom when in reverse

SMullenMaine

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I have a 96 volvo Penta 3.0 with an SX-C1 outdrive on a Larson Bowrider... I was recently towing another boat in reverse (unusual situation)... and after 4 minutes I was ankle deep in water.

the boat has been on a mooring for years without an automatic bilge pump and is quite dry otherwise...

I have tested it, and water comes in thru the cut in the transom beside the large exhaust manifold... but only while under load in reverse.

The attached pic shows the transom on the left, flywheel housing right, exhaust and flooding...

What could it be?

Thanks, Steve Mullen, Portland, Maine
 

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Don S

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Re: Flooding thru transom when in reverse

You need a new transom in the boat. The wood in yours is rotten. VERY common problem on boats.

The only repair is to remove the engine, drive and transom shield and rebuild the transom.. If you look over in iboats Restoration and hull repair forum, you will find all kinds of information on transom repair.
 

Bondo

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Re: Flooding thru transom when in reverse

I have a 96 volvo Penta 3.0 with an SX-C1 outdrive on a Larson Bowrider... I was recently towing another boat in reverse (unusual situation)... and after 4 minutes I was ankle deep in water.

the boat has been on a mooring for years without an automatic bilge pump and is quite dry otherwise...

I have tested it, and water comes in thru the cut in the transom beside the large exhaust manifold... but only while under load in reverse.

The attached pic shows the transom on the left, flywheel housing right, exhaust and flooding...

What could it be?

Thanks, Steve Mullen, Portland, Maine

Ayuh,.... Welcome Aboard Steve,... Always good to see another Maineiac on board....

Yer boat has a very, Very Rotten transom.....

Find a heated garage, 'n you've got yer winter project all lined up....
 

tpenfield

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Re: Flooding thru transom when in reverse

Yes, I add my vote to the rotten transom thought.

The "best case" scenario is that the transom assembly seal is failing and the pulling force of the engine in reverse is opening a gap that allows the water to come through. However, usually there is a soft transom that allows the movement in the first place. Regardless of the exact issue, it is time to take things apart and open things up for a good look. Have the checkbook handy.

BTW - congrats on taking an excellent picture of the issue. Usually pictures posted of problem areas are no where as easy to decipher as what you have posted.

Bond-o: I wonder if he is a "Maineiac' or a 'Mainer' ??? - Steve let us know.
 

SMullenMaine

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Re: Flooding thru transom when in reverse

Well..... you are all very correct!

I reached back to touch the perfectly smooth white transom and thought that I was touching an insulation panel... you know that stuff that's padded yellow fiberglass with a layer of white plastic on one side?

It turned out that the white layer was a coat of spray paint which covered the confetti that remained of a $7 sheet of chip board... there is nasty black rot or mold, but also no evidence that there was ever any glue holding the chips together! no fiberglass on the inside!!??

The top of the panel seems fairly solid... and the 2' x 2' section of marine ply in the center seems good... but now I can see that the bolts on the lower side of the transom collar have been tightened 3/4" INTO the plywood.

The good news seems to be that once I pull the engine I can increase the strength of the transom 100 times by using only a putty knife and a skilsaw and a nice slab of marine plywood.

Thanks, Steve
 

Don S

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Re: Flooding thru transom when in reverse

The good news seems to be that once I pull the engine I can increase the strength of the transom 100 times by using only a putty knife and a skilsaw and a nice slab of marine plywood.

There is more to it than that, I'm going to move this thread over to the hull repair forum. No doubt you will get some better repair information.
 

Bondo

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Re: Flooding thru transom when in reverse

Well..... you are all very correct!

I reached back to touch the perfectly smooth white transom and thought that I was touching an insulation panel... you know that stuff that's padded yellow fiberglass with a layer of white plastic on one side?

It turned out that the white layer was a coat of spray paint which covered the confetti that remained of a $7 sheet of chip board... there is nasty black rot or mold, but also no evidence that there was ever any glue holding the chips together! no fiberglass on the inside!!??

The top of the panel seems fairly solid... and the 2' x 2' section of marine ply in the center seems good... but now I can see that the bolts on the lower side of the transom collar have been tightened 3/4" INTO the plywood.

The good news seems to be that once I pull the engine I can increase the strength of the transom 100 times by using only a putty knife and a skilsaw and a nice slab of marine plywood.

Thanks, Steve

Ayuh,.... Got any pictures of the carnage,..??
 

SMullenMaine

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Re: Flooding thru transom when in reverse

Bond-o: I wonder if he is a "Maineiac' or a 'Mainer' ??? - Steve let us know.

I'm a Mainer because I live in Maine.... but I'm a Manieac because I own a boat too.

so.... pulling the engine sounds pretty easy... 10 steps... how hard can that be? and I have a 3 ton bridge crane...

How much disassembly do I have to do to the stern drive before I disconnect it from the inner transom flange??? is it just the shift linkage and the trim sender?

Steve
 

SMullenMaine

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Re: Flooding thru transom when in reverse

Well, here a couple of pics showing chunks of transom I removed by blowing on it lightly. ;-)

There seems to be a oval section extending 4" left and right of the 3/4 marine plywood at the center of the outdrive... the top and (surprisingly) the bottom of that panel seem ok...

IMG_3190.jpg
 

oops!

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Re: Flooding thru transom when in reverse

you can use marine plywood for the transom.. it wont really give you much added benefit.

i use exterior grade plywood....(not chip board) its almost the same as marine grade at that point.

once the motor is out... you will need to remove the inner transom plate, the steering assembly.. and the outer plate.

get everything out of the way.

using a grinder, pry bars.. a circular saw... what ever you can... remove all the rotten wood WHILE LEAVING THE OUTER HULL SKIN IN TACT.

after the removal.. post pics and we can guide you thru the replacement
 

SMullenMaine

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Re: Flooding thru transom when in reverse

ok.... The transom came out with only a putty knife... IMG_20121123_160500_575.jpgIMG_20121124_135321_942.jpgI made a template of the old one before I crumbled it. It consisted of one piece of 3/4" OSB with another piece of 3/4" plywood (approx 2' x 2') in the center.

I plan to buy a sheet of Marine Plywood 3/4 thick... cut out the two sections and bond them together with West Epoxy... I'll put it in place and make all of the cutouts and drillings... and then "paint" it all with West Epoxy...

Then I'll take a big section of fiberglass mat and soak it in catalyzed fiberglass resin & apply it to the contact surfaces between the fiberglass hull and the plywood and clamp it all together...
IMG_20121124_141423_434.jpg
Does this seem right? Any hints?

Thanks! Steve... Portland ME, 20 degrees F
 

Woodonglass

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Re: Flooding thru transom when in reverse

If you use epoxy the way you describe you will need to use it on everything. Poly resin does NOT stick to Epoxy. Not saying you can't use it, just wanted you to know that once you start you're in for the long run and the added expense. Poly would work just as well for a lot less money.
 

jigngrub

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Re: Flooding thru transom when in reverse

Polyester resin is cheaper, but has a strong odor with noxious fumes and requires a respirator to be worn when working with it. It's also flammable.

Epoxy resin is nearly odorless with no noxious fumes and doesn't require a respirator to be worn when working with it. Epoxy resin is not flammable.

Epoxy resin is my friend, polyester resin is not.
 

SMullenMaine

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Re: Flooding thru transom when in reverse

I think that I will use the epoxy all of the way through... I have plenty left over... I just built a Shellback dinghy.

I am really cautious around the epoxy... I had a pretty frightening allergic reaction to it a few years ago... one side of my face & mouth blew up like a balloon... Wear the mask!
 

ondarvr

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Re: Flooding thru transom when in reverse

People frequently equate odor with toxicity, the two are unrelated. While neither product is good for you, epoxy has the potential for a much more severe and rapid negative reaction than polyester.
 

jbcurt00

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Re: Flooding thru transom when in reverse

I am really cautious around the epoxy... I had a pretty frightening allergic reaction to it a few years ago... one side of my face & mouth blew up like a balloon... Wear the mask!

You might want to google: epoxy sensitivity

For some, being exposed to the lingering fumes in a tented enclosure from a epoxy work done week ago is enough to cause an allergic reaction. It could be from overexposure once (having even small amounts of epoxy land on bare skin) or from repeated long term exposure (working w/ epoxy daily for several hours per day).

The sensitivity may or may not be what you experienced, but it might be something you might look into. And makes sure you're using the chemical fumes filters.

Full face respirator may help too.....

But if you've become allergic to epoxy, it can go from bad to worse very quickly, as ondarvr suggest above..

Rehab safely, and I look forward to seeing your progress
 

superpop

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Re: Flooding thru transom when in reverse

Have you also checked the stringers for rot. Might as well replace those along with the deck if it has rot in it. Hopefully it is just the transom but in most cases when there is rot like what you have, it is everywhere.
 

SMullenMaine

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Re: Flooding thru transom when in reverse

Well, here it is... new transom... 3/4 marine ply, with a thicker section laminated on with titebond III. The thicknesses and shape match the original transom except that it was OSB with a ply overlay on the thicker part. I have put 2 coats of epoxy on the new transom.

IMG_20121125_122653_838.jpgIMG_20121205_183122_109.jpg

I plan to mix up epoxy with colloidal silica to Mayonaise and apply it to the inside of the fiberglass transom... (any hints on how to spread it properly?) Then I'll clamp it through the rough-cut that I made for the out-drive and wedge it against the stringers.

I'm concerned about the port and starboard wings of the transom... they weren't touching the fiberglass skin at all at these points and it looked like the pocket behind the wood transom became a bowl that water couldn't escape and the rot there was phenomenal. Should I fill that pocket?... with what? expanding urethane foam?

After that, I'll need advise about treating the through-hull cutouts and drillings properly so that my grandkids don't have to do this... I'm concerned that in another decade there won't be any handy-people left on the planet...

Thanks for being here now!

Steve
 
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