RE: [omc-boats] How to check stringers/foam?

From: Tom Paquette <tpaquette@...>
Date: Sun, 2 Jul 2006 10:51:43 -0400

Thanks David,


I have an outboard. So in that respect I think my task may be somewhat
easier to attack. But removing an engine is removing an engine….


I removed the rear seating section using a sawsall type saw cutting along
the seam. The transom was dry rotting. That wood has been removed. I then
removed all the floor as it was rotting in places as well.


So What I have now is an empty shell. Except the front seating section
which I dug out with a crowbar and a shovel using extreme care not to put
pressure on the hull. The rest I cut out with a knife style keyhole saw I
picked up at Lowes for around $10. I still have a small amount to dig from
the front.


Here is a photo of current state. As you can see the front area is still
damp as I dug out from under the front this am.


The dark areas in the middle are where there was more resin applied during
the original building.


The bar clamp I put in place before removing the rear section to ensure the
upper hull stayed somewhat in proper dimension.


Note if you look close there are two small bolts glassed into the hull to
hold motor mounts. Wow a 14’ boat with an inboard that would be


Anyway, Where do I go from here? Sound like you made sure the hull was
level. Then poured in foam. Can you detail a little more your method of
“leveling” the foam? Sound like you went slow and hacked out any high
spots. How did you ensure a final level surface for the floor support (Ie.
No voids under the wood..).


I was thinking of building a jig section from the future floor. A 4 foot
piece that I would bracket on the sides using framing above to hold in
place. I was going to staple plastic onto the under side of the jig so the
foam would not stick to the jig. Then I assume the foam would expand out
past the section rather than pressuring the floor or hull.


Any and all thoughts would be highly appreciated.



Charlotte, NC






From: owner-omc-boats@... [mailto:owner-omc-boats@...] On
Behalf Of David A. Avedesian, PE, RPA
Sent: Saturday, July 01, 2006 6:54 PM
To: omc-boats@...
Subject: RE: [omc-boats] How to check stringers/foam?




I have a few questions first in order to understand your application.


Have you removed a section of floorboard? Or have you cut hole into the
floor and use the hole like the opening of a mine. You have reached into
the hole and ‘mined’ as much wet foam as you can by reaching into the hole.


I am really asking you to describe what your condition is right now.


Yes you want to be concerned about over and also under foaming. Over
foaming can push up the floorboard. Under foaming will leave voids of


The method I used was a complete floorboard replacement. We foamed in
batches. As we mixed a new batch we would overlap and over foam the area.
Once the foam had set, we would pull a string from edge to edge and then
using a cheap steak knife, we would cut the foam down to the height of
finish floor minus the thickness of the new floorboard. In my case, my new
floorboard was ” marine plywood.


A few questions and a few directions,


David Avedesian

Silver Spring, MD




-----Original Message-----
From: owner-omc-boats@... [mailto:owner-omc-boats@...] On
Behalf Of Tom Paquette
Sent: Saturday, July 01, 2006 10:28 AM
To: omc-boats@...
Subject: RE: [omc-boats] How to check stringers/foam?




I have one question.


I have removed the foam and hull is now empty and dry. I kept a few edge
spots for height determination. I plan to pour a little new foam beside
these spots level it with them and pull up the last few pieces of old foam.


Once I glass the new floor to hull following the sealing methods you
prescribe… HOW do I know how much foam to pour into the chamber?? I know I
have to have a couple of pouring/release holes. How many holes do I
need?? Is it possible to over foam and crack or deform the hull?? Or am
I being over concerned….



Anyone who has done this part your advise would be highly appreciated.



Charlotte, NC


From: owner-omc-boats@... [mailto:owner-omc-boats@...] On
Behalf Of David A. Avedesian, PE, RPA
Sent: Friday, June 30, 2006 10:14 PM
To: omc-boats@...
Subject: RE: [omc-boats] How to check stringers/foam?


Zach in Seattle:


If you have water in the foam, the floorboard is bad. OMC did not protect
the wood floor from the bottom. The wood is open or raw.


My suggestion for the easiest and best method is as follows:


* Make a mark a straight cut line two inches from the side of the

* Then draw a cut line about two inches in front of the bilge well

* A cut line between the front and back seats.

* Using a hand skill/7" circular set the saw blade for a 1/2" cut and
saw cut the floorboard.

* Remove the floorboard and send it to 'heaven'.

* Using a claw hammer’s claw, remove the foam and send it to

* If you have any mildew/mold, wash the inside of the hull with
bleach and water.

* Then rinse and dry the inside.

* Note: When I removed the foam, I decided to make a custom fit
stainless steel gas tan to fit down in between the stringers. I made the
tank 8 feet long x 11 inches wide with a varying depth of 7 inches in the
front to 4 inches in the back. The new gas tank held 27 gallons of fuel
and place the weight as low in the center of gravity as possible. It has
worked great and freed up valuable space in the back of the boat. The trim
on the boat greatly improved. The down side of this option was the tank can
be very expensive. For me the benefits out weight the cost.

* By leaving the two inch edge on the side of the boat, it becomes
easy to rematch the floorboard height within the boat.

* Use the finest grade marine grade plywood (5 ply) you can buy.

* Cut the pieces to fit the void created by removing the old floor.

* ‘Paint’ all six sides of the new floorboards with epoxy. This will
seal the floor from moisture in the future.

* Re-foam using the highest density closed cell foam system under the

* The floorboard does not touch the boat stringers.

* The floorboard is supported by the foam. The foam becomes part of
the structural support of the boat.

* The floorboard ‘floats’ above the stringers.

* The floorboard is ‘hard’ at the edges to the boat.

* Use one layer of tri-axial fiberglass cloth and epoxy the new floor
board in place.

* Sand and paint the floor a dark gray interior paint.

* ‘Float’ a carpet over the new floorboard.


When you take hundreds of pounds of water out of the basement of the boat
and you hit the gas, the boat just want to jump out the water. She can not
be on plan with in 12 feet. Now that is a boat.


If you would like to view the finished product, I sent my Sweet 16 to my son
in Seattle, WA. In fact, he is almost out on it every week on Lake Union
and Lake Washington. The boat is all white with a black rubrail with a 115
hp Yamaha. If you see the boat, my son’s name is Greg.


Good Luck,


David Avedesian

Silver Spring, MD






-----Original Message-----
From: owner-omc-boats@... [mailto:owner-omc-boats@...] On
Behalf Of Zach Stanley
Sent: Friday, June 30, 2006 11:57 AM
To: omc-boats@...
Subject: Re: [omc-boats] How to check stringers/foam?


This is a topic that has had me waking up at night screaming! I know that
our boat is waterlogged. It has sat low as long as we've had it - about
three years - but also lists to the starboard side. Also, the boat has been
in the family since new and everyone has commented how "the boat just kept
getting slower and slower" and "harder to pull a skier out", etc. Makes
sense now that the boat is dragging some extra weight around.


My question is... will replacing the foam using conventional methods now
give the boat structure as the original injected foam did. I would love to
hear comments about regained performance - or hull-flex post foam repair.
Pictures of the repair process would be great. Perhaps a section on the
ultimate site should be devoted to this subject with tips and photos since
it is such a common problem. Someone had mentioned cutting large holes in
the floor at intervals to scoop out the foam and re-fill the cavity while
leaving the floor basically intact. I think I will try this if the floor
itself can be saved. If that person has any pictures or further tips I
would love more info. I feel very fortunate to be involved with such an
informative group - thanks guys!


1970 Seasport 155

Seattle, WA





> ----- Original Message -----

> From: "Andy Perakes" <aperakes@...>

> To: omc-boats@...

> Subject: Re: [omc-boats] How to check stringers/foam?

> Date: Thu, 29 Jun 2006 20:49:12 -0400



> I haven't tried this, but another thought that would be a lot less

> destructive (if it works): Remove one of the bolts holding the seats down

> and try sticking a pipe cleaner (the fuzzy wires used in arts & crafts) or

> some other object that might show moisture into the foam. I'd recommend

> trying one of the front bolts as both my rears were rusted in place and

> ripped the lock nut out of the plywood when I repaired my seats 2 years

> (both fronts came out easy). As I said, I haven't tried it yet, but its

> quick and easy enough to be worth a try before cutting holes in your floor

> (though that's probably the only way to be 100% sure....but then how many

> holes do you cut and where?) Good luck!


> ----- Original Message -----

> From: "David A. Avedesian, PE, RPA" <david.avedesian@...>

> To: <omc-boats@...>

> Sent: Thursday, June 29, 2006 6:56 PM

> Subject: RE: [omc-boats] How to check stringers/foam?



> > Kenneth:

> >

> > I own a 1965 Sweet 16 outboard model.

> >

> > Generally there is never a question regarding whether you have water or

> not.

> > If you have water under the floor boards, the boat is very heavy and

> > very low in the water in the stern.

> >

> > I believe the easiest and effective way to check is to use a hole-saw

> > perhaps 3" to 5" in diameter and drill through the floor in the center

> > front of the rear combing.

> >

> > The floor board is about 1/2" thick and there is nothing under the

> > line of the boat from a structural point of view.

> >

> > As soon as you remove the round plug, you will know by the odor. The

> second

> > way to determine is to push your finger into the foam. If it squeezes

> > water, than you have a problem.

> >

> > I have found that when it comes to water under the floor boards, you

> > never be sort-a-pregnant. It will either be zero or flooding.

> >

> > If you are dry, then mix up a small amount of epoxy (West System is what

> > have used) and a layer of tri-axial cloth. Tri-axial is strong in three

> > directions and you can use one layer.

> >

> > This may be more information than you wanted but I have asked this

> question

> > a couple of times. If you would like more, feel free to ask.

> >

> > David Avedesian

> > Silver Spring, MD

> > Near Your Nation's Capital

> >

> > -----Original Message-----

> > From: owner-omc-boats@... [mailto:owner-omc-boats@...]

> On

> > Behalf Of Kenneth Fingerlos

> > Sent: Thursday, June 29, 2006 4:21 PM

> > To: omc-boats@...

> > Subject: [omc-boats] How to check stringers/foam?

> >

> > I've seen a lot of traffic on this list about the state of the foam and

> > stringers underneath the floor.

> >

> > Does anybody have any sage advice as to how one would go about checking

> the

> > status of such things? In particular, can it be done without cutting

> holes?

> > and if one has to cut a hole, where should such be cut to maximize the

> > benefits and minimize the problems?

> >

> > Thanks,

> >

> > Kenenth

> >

> >

> > -----

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> >

> >

> > -----

> > To get off this list send mail to omc-boats-unsubscribe@...

> >


> -----

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