Permissible moisture readings for repowering?

KS1

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Hi All,

I am picking up my 1995 GW Islander 268 next week. The surveyor had a few recommendations on the transom, but i'm wondering if i should have it replaced since i'll be repowering it from a single 1995 Yamaha 250 to twin Yamaha 150's or 200's. He said:

"Cracking around the cap should be fixed to prevent further moisture from entering the transom core. Areas around the cracks on both port and starboard side of transom had moisture readings in the 16 - 17% range while the rest of the transom was in the 13 - 15% range." What is a permissible transom moisture reading? He never said it was bad enough to warrant a complete re-build, but what do you think i should do? I have a fiberglass tech who claims the only way to know for sure is to drill holes, but i don't want to do that without having them sealed up right away. Guess i could have him do it...

Also, for repowering, my local marine mechanic suggested going with maximum horsepower (400hp), but i'm wondering if i will be able to travel slow enough to troll without using a kicker or drift sock.

Thanks in advance!
 

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seasick

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How long was the hull out of the water? It's best to not test the same day the boat was hauled .
It might would help to know what the readings were lower down towards the paint line as well as readings on other parts of the hull. Did the surveyor happen to measure the transom moisture from inside the bilge?
If the readings get higher as the meter gets closer to the transom cap, that would be somewhat normal on a hull with that cap.

The cracks worry me more. Changing to twins can put higher stresses on the transom when the motors are run in opposite directions. In addition, the 150s will weigh more than the single 250. It would be advisable to pull the motor and the cap and inspect what lies below.

If pulling the motor is a problem right now, you can remove one of the engine bolts and see what the core looks like. You can replace that bolt and remove more one at a time. Same goes for the kicker bracket. I would feel better having someone knowledgeable check the strength of the transom
 
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KS1

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The boat has been out of the water since October of 2019 and the surveyor only took moisture readings from the outside. I'm trying to sell the old motor on Craigslist, then will have a fiberglass tech give a better opinion once it's more open.
 

seasick

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Moisture tests on hulls that have been on dry land for extended periods can be inaccurate. Let us know how things turn out.
Good luck with the boat!
 

KS1

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The seller actually gave me a copy of a survey from a week or so after he took the boat out last year and it was basically the same moisture content as the one I just had done. I had the second survey done because I wanted to make sure it wasn't worse and because it was on the hard for a year.
 

seasick

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The seller actually gave me a copy of a survey from a week or so after he took the boat out last year and it was basically the same moisture content as the one I just had done. I had the second survey done because I wanted to make sure it wasn't worse and because it was on the hard for a year.
That fact is a surprise to me. I would expect the moisture reading to change. Usually right out of the water, readings can be higher than actual and after long stints on land, assuming a dry bilge, will typically be lower.
I am not an expert on moisture meters. I only know what I have been told by surveyors and what I have read about interpreting the data. As I said, good luck and keep us informed
 

KS1

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Thanks, will do!
 

KS1

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Brought the boat down last Thursday! It's at my local marina and I had them and the fiberglass tech look at it. Their initial reaction is I got a steal. Will see when the motor is removed later this week and I can get it to the tech for further work on sealing up the transom. Initial quote for fiberglass repairs and bottom paint is roughly $3k.
 

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efx

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Does the transom move at all when you stand on the motors anti ventilation plate? Is the transom swelling at the areas where the motors bolts do not keep it tight? Was the boat stored in a location where it gets below freezing? If the transom moves at all, rebuild it. If it’s swollen significantly, rebuild it. If water is in it and it gets below freezing, it delaminates. Rebuild it.
 
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KS1

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No, transom checked out with the tech and my marine mechanic. They said it's fine and if you hang on the motor, the transom doesn't flex at all. Seems solid
 
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Pat Hurley

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No, transom checked out with the tech and my marine mechanic. They said it's fine and if you hang on the motor, the transom doesn't flex at all. Seems solid
...those readings look acceptable. I have taken readings on many a transom. As the previous poster stated about swelling outside of where the motor is mounted is an indication of excessive moisture. If that is not present I would seal the cracks and move on unless you discover otherwise upon removal of the motor.
 

KS1

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Yes, that's the plan. Fingers crossed when the motor comes off and the fiberglass tech removes that strip of aluminum angle iron. BTW, he is planning to fill the old bolt holes, glass over the transom cap (aluminum angle iron removed) and ferret out the glass along the outside of the transom. Just wondering why Grady continued to use the aluminum strip when they knew of possible moisture inclusions over time?
 

Pat Hurley

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“Just wondering why Grady continued to use the aluminum strip when they knew of possible moisture inclusions over time?“

Einstein’s theory
 

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Mine was fine, one soft spot on one the bottom bolts when I repowered year and a half ago. The fiberglass guy said in the near future a yearish I will need a new Transom. 1998 Grady White Voyager. I would do it now and not be worried. My guy said $3000 Better than it was new. Why mess around ?
 

KS1

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Yeah, I will certainly go with whatever he suggests once it's opened up. I want assurance that it will last 5 - 10 years. If he can't guarantee that, I'll have the transom redone for sure.
 

KS1

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I called Grady yesterday. They said that in 2000 they moved the scuppers on all hulls up 1.5" to accommodate the new, heavier 4 strokes that were hitting the market (so they are not submerged). So I'll be moving the scuppers on my 268 up too. Just FYI for those thinking about repowering older hulls or those that already have. A hose clamp or hose fail would be catastrophic offshore...
 
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TUNAHUNTER197

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I called Grady yesterday. They said that in 2000 they moved the scuppers on all hulls up 1.5" to accommodate the new, heavier 4 strokes that were hitting the market (so the scuppers are not submerged). So I'll be moving the scuppers on my 268 up too.

Was this just specific to the 268 model or all 2000 models?
 

KS1

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It was all models year 2000 and newer, not just the Islander.
 

seasick

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You are going to have to raise the water line for the bottom paint
 
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