25 Oday Stern Water Intrusion

RECESS · Apr 10, 2010

Hello Huffwahoo,

It seems I am determined to get my 6ft 220 lb body into every nook and cranny in my boat. I had that 1/2 plywood fail me while motoring. The outboard lurched forward and cracked the transom. I also cut the fiberglass and was able to remove 70% of the plywood easily. I chipped another 20% of that filler they used and the wood that stuck to it. That last 10% was a real mother. I finally got out my metal grinder and was hesitant as some of the marine sealant does present an explosive situation in a enclosed non ventilated are. You do not get more an enclosed area than that coffin under the cockpit. I ran a fan, but I think there is still quite a bit of danger with grinding in such an enclosed area. I wore a full chemical respirator and only grinned for a couple minutes at a time with a large fan blowing from the coffin berth. That filler comes off fast with a grinder but it is a dusty mess.

I am just preparing to put in my 1/2 inch plywood that I will also have an aluminum sign to secure the bolts.

As to your question about two 1/4" pieces vs a 1/2" piece. If you go the 1/4" route you will need to be able to wedge enough boards to press it in the same arch of the glass without bowing out the glass. In the end I decided to go with a 1/2" piece with marine sealant on the backside to the fiberglass. I have a large crack that allows me to fill after the board is in place. I took a straight 2x4 and laid it across the glass once I had removed all the wood and there really is not that much curve that filling it is too much.

I am going to be curious if the full piece that I cut using the fiberglass piece that I removed as a template will be able to go there in one piece or if I will have to cut it into two pieces and glass it in. I am also adding a swim ladder so I will be adding 1/2 inch to the other side of the transom.

I am in the process right as we speak. My wife brushed the dust off me as I walked in. Let me know how you progress and I will share my learning curve with you.

wonkodsane · Apr 10, 2010

Oh wow, Dave, that looks painful!

We have an 8HP Mercury 4 stroke on our 23', so we're a little overpowered, but it's what came with the boat, so it was a take it or leave it situation. We ended up getting the heavy duty Garelick "Eez-In" bracket and putting a big piece of 1/2" starboard on either side and then securing it with SS carriage bolts, washers, and locknuts. It has kept that whole section of stern flexing together. The 1/4" marine ply that was inside wasn't just in poor shape, but only half of the old lightweight Garelick was even through it, the other was straight through the glass with no firring or other support ("stars" around the old holes). I'm glad we fixed it or we might've lost a motor, looks like you were lucky too.

RECESS · Apr 10, 2010

It was a bit painful to end my sailing season but I really have not been bummed about the failure. I have loved so much bringing this boat back. I had a serious dock ding in the front that structurally had to be dealt with. If you follow the blue accent strip to the front you will see it just is not right. I grinded it down to just glass and built it back up. I have had a ball restoring this boat. I once took on a 1974 Corvette, it turned some heads but I never got it where I saw it should be in my head. I have enjoyed doing the structrual work as much as the cosmetic. I love sailing her, but second to that I love working on her.

jibes138 · Apr 11, 2010

I'd go with the 1/4 inch laminated. It will be a lot easier to work with. I built a small sailing and rowing dinghy and the stern is three layers of 1/4 inch marine plywood laminated together. Very strong when completed. I wouldn't mess around with polysulfide or marine tex. Just use West epoxy mixed with microfibers to give it a thicker consistency. It will do the same function as the other fillers but add a lot more in strength to the joint. Be careful working with large batches of epoxy, you need to work in small batches. I tried to mix a large amount on a hot day once and it kicked over so fast and became so hot you couldn't touch it without getting burned. Taught me a lesson. another trick is cool in in a freezer or ice chest, the lower temperature will slow the reaction time to give you more time to work. If you freeze it it becomes extremely thick but thins out again as it thaws. I froze some a few times so I could save excess, it is so expensive I didn't want to waste it.
Recess looks beautiful, it is a real shame the motor bracket damage, but not catastrophic, so your repair should keep her going for another 30 years. Definitely use solid glass and epoxy where the screw holes will go. I wouldn't use straight epoxy for the holes as it will be under various loading conditions. Better to laminate the area or at least use epoxy mixed with some agent to give it more compressive strength. That way if it leaks no big deal until the boat sinks. :>)

RECESS · Apr 11, 2010

I had to cut the plywood into two pieces to be able to manipulate it into place. I doubt I will have to use any filler. I will just buld up the fiberglass with resin and mat in layers to take all curve out of the inside of the transom and then glass in the sealed plywood.

sailingdog · Apr 12, 2010

RECESS said:
I had to cut the plywood into two pieces to be able to manipulate it into place. I doubt I will have to use any filler. I will just buld up the fiberglass with resin and mat in layers to take all curve out of the inside of the transom and then glass in the sealed plywood.

Make sure you fill the cut between the two pieces with at least thickened epoxy.

RECESS · Apr 12, 2010

sailingdog said:
Make sure you fill the cut between the two pieces with at least thickened epoxy.

Absolutely. After having to make the cut, I will glass in one and then the next so I do not have a soft area that could twist or bend between the two. They used one continous piece of plywood so they had some support for the kicker mount and then all the way to the middle for the grudgeons. I also plan to put in a piece of aluminum sign that over laps the kicker bolts and extends over the cut so ther is no flexing. It would have been great if I could have got the whole piece in, but I think the top of the boat would have to be removed for that.

kenn · Apr 12, 2010

huffwahoo said:
...
My approach is to replace the half (1/2) inch plywood with two one quarter (1/4) inch layers of marine plywood . My concern, I will not have the ability to mold the half (1/2) inch plywood to the contour or the shape of the stern; where as one quarter (¼) inch provides greater flexibility. My intentions are to bed the first layer of plywood against hull with a polysulfide or Marine-tex® epoxy.. This will fill any small voids between the hull and the plywood. Then apply a layer of fiberglass epoxy (West-system) then apply the second sheet and apply three layers of glass and cloth.

Using 2 sheets of 1/4" plywood, epoxied or otherwise glued together, sounds reasonable. I wouldn't use polysulfide, I would only use epoxy for this job, thickened with Cabosil or chopped glass cloth when necessary.

I would also use nuts and bolts or woodscrews freely to temporarily secure the plywood layers as they are installed, then just back them out and fill the holes with epoxy.

RECESS · Apr 12, 2010

One of the other advantages of using two 1/4 inch pieces is if you need to cut them to maneuver them into place, you can make the cuts a foot apart from each other so they come together in two different places and you have overlap. I think it would be easier to build up the fiberglass to make it a flush mount of the plywood than to try and warp the plywood to fit. Building up the fiberglass also strengthens the transom.

25 Oday Stern Water Intrusion

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