Need to repar transom on O'day 25

[Tito C.]

I bought my O'day 25 recently, and even though for the most part is in good shape, one day while wandering under the cockpit, I noticed a 4" crack on the inner part of the transom. To my surprise when I touched the surface it felt soft, and that's when I noticed four bolts right above the crack. Oce out side of the boat I realized these were the bolts attaching the outboard mount to the transom.
I touched the fiberglass outside around the area where I had seen the crack (inside) and it is definitely stronger, but I could tell it had caved in a little (the 9.9 motor was/is currently mounted).

Can anyone advise me on hot I can repair reinforce this. Any way I had been planning on replacing the motor mount for a Garelick modern one, so this might be the chance to take care of all this.

Thanks,
David

 

[Napa Ed]

wiggle room

You can wander under the cockpit? You must be tiny. There are other posts here if you search the archives for transom O25 or similar. I suggest head to toe tyvek and a respirator. I use a 3M hepa airmate hood that's comfortable for long stints in cave like environments. How's your yoga going? You'll need a combination of upward facing dog and yogic sleeping position (and a good grinder)
Then; bring on the resin. Woo-hoo.
http://www.hepas.com/CFS/3m_hepa_air.htm

 

[HukilauMike]

What's soft?

The type of repair you need will be determined by the damage itself. What is in fact, "soft"? If its core material, then you will need to remove all of the spongy, rotten wood, suck out all of the moisture, and either replace the core and glass over it (if the damaged area to bigger than say five by five inches); or if the area is small enough, just fill with thickened epoxy. You have the advantage of not having to worry about cosmetics if the outer gelcout is intact and all you are doing is working from the bilge side. However, if there is no core material, I would be worrying about why the area is soft. I don't know how you would get a hull blister above the waterline (I am assuming this is above the waterline), but mushy epoxy is a serious problem beyond my humble experience and abilities.

 

[Tito C.]

Transom Repair

Mike:

I should be more specific. When I said soft, maybe I should have said weak. What I can see from inside is the white wall of the transom. The material just looks like heavy fiber glass, but it has the crack I mentioned before, and when I touched it I could move the material around the crack. Excuse my ignorance, but what do you mean by core material?

Thanks,
David

 

[HukilauMike]

Core material

Fiberglass boats are often not made with 100% fiberglass. Fiberglass is actually a stronger and lighter building material if it is layered with something else. Oday and many other boat builders used end-grain balsa wood as a core material in its boats. The decks on most fiberglass boats are cored; there is a layer of balsa or plywood sandwiched between fiberglass layers. If water gets into the wood, it will rot, causing the fiberglass to delaminate (separate) from the wood core. This creates weak areas that if not repaired or contained, will spread and could lead to real structural problems. Delamination can also be sped up by a freeze-thaw cycle.

While Oday and most boat builders used cored decks, most less expensive boats (including Oday) did not build cored hulls. However, I have heard of Oday using core material on some transoms, probably because of the high loads caused by rudders and motor mounts. Its easy to tell if you have a cored transom. Remove the motor mount, and look at the bolt holes. If your transom has core construction, it will look clearly like a sandwich. The core material may appear very mushy if there has been water intrusion. Jim's post suggests one way to remove wet core. I have also heard of people using a drill with a bent nail; if the ruined core extends beyond the reach of the nail in the existing holes, you will have to drill new holes (not all the way through the transom; just deep enough to reach the core). Keep drilling holes until you find dry core. Either way, its a messy job. There is also a product called "Git Rot". It is a liquid that you pour or inject into the affected area that is supposed to repair spoiled fiberglass core. I have never used it, but I have attached a link to a q&a about it.

It is generally recommended that after you remove the wet core, you redrill the existing holes (the ones you need to use; the ones you drilled just to get at core just get filled with epoxy and maybe some chopped up fiberglass mat) a few sizes bigger than you need, then refill them completely with solid epoxy. Once that dries, you drill them again with the correct size bit. That way, if water intrudes again through those holes it won't touch the core material, only epoxy.