Small Crack on Inside of transom looks like Fiberglass only. Should i be worried?

[TomToms]

So, I was doing some maintenance on the my boat (18ft 1979 Thunderbird TriHull w/ Mercury 115HP inline 6 motor) and I noticed that there are two bolts coming through the boat on the inside of the transom, they look to be some bolts for the engine mount. there is a crack in the fiberglass running in-between these two bolts. its about 10 inches long. Is this something I should be worried about? Should i add an aluminum brace (sandwich bracket) Or look at redoing the transom? I am at work right now, but I'll take a pic when I get home and post that for more clarity.

 

[Watermann]

Worst case, it could be that the transom wood has become compromised and is allowing the glass to flex too much causing the stress crack you're seeing.

 

[TomToms]

Whats the best way to check if it's be compromised?

 

[fhhuber]

Drill...

Drill a test hole about 5/16 inch dia and 1 inch from each place a bolt penetrates the transom. If the wood is wet you have issues. If you can probe in and find it soft with a small screwdriver you have rot.

If its OK... Epoxy and shredded fiberglass fill the holes.

If its not OK.. you may be about to loose your engine.

I found the cracks on each side of the engine mount... Grabbed my engine's lower end and could move it around... a lot... watching the transom flex.
Drilled... it was all rotted.

I found a different hull.

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Ooops looks like you got an inboard/outboard... I have outboard. You probably can't manipulate the drive as easily if its rotted...

 

[TomToms]

Drill...

Drill a test hole about 5/16 inch dia and 1 inch from each place a bolt penetrates the transom. If the wood is wet you have issues. If you can probe in and find it soft with a small screwdriver you have rot.

If its OK... Epoxy and shredded fiberglass fill the holes.

If its not OK.. you may be about to loose your engine.

I found the cracks on each side of the engine mount... Grabbed my engine's lower end and could move it around... a lot... watching the transom flex.
Drilled... it was all rotted.

I found a different hull.

So If I grab the lower end on my motor, and move it how much flex should the transom have? Or should it be completely solid?

 

[fhhuber]

Need to find someone with I/O and rotted transom experience...

I don't know when hand moving the outdrive how much flex means trouble for those.

The drill test works on anything.

 

[Watermann]

His motor is an OB Merc, the cracking is on the inside between the mounting bolts.

Yeah the bounce on the motor can show no flex but it's not the best method, pull the bolts one at a time and probe the wood to see if its wet, dark and rotten.

 

[TomToms]

His motor is an OB Merc, the cracking is on the inside between the mounting bolts.

Yeah the bounce on the motor can show no flex but it's not the best method, pull the bolts one at a time and probe the wood to see if its wet, dark and rotten.

Ok, so if the wood is still solid then i just seal up the fibre glass and I'm good to go? Im thinking I'll only have this hull for another 2-3 years, if there is rot, would something like 3x3" aluminum angle spread across the entire transom from the inside help reinforce it to last me?

 

[Watermann]

Check the wood first, that's pretty high up on the transom wood so if it is rotten then just know it rots from the bottom up. It doesn't have to be cracked from rot, that's worse case, it could be age combined with other factors like motor weight, being trailered without a motor toter or bolts being over tightened.

 

[jbcurt00]

To be clear, the core sample holes are drilled from the INSIDE of the transom and are ONLY supposed to be 1-1.25in deep. NOT all the way thru the transom.

Post some pix if you can before you drill. As gelcoat and fiberglass ages, it can develop fine cracks but if the thru bolts have compressed into the glass, thats not a good sign

 

[TomToms]

I will post pics as soon as I can. I think its a crack full through the fibre glass not just a hairline or surface crack.

 

[gm280]

TomTom, drilling IS the best option. But I would also drill at the lower section of the transom too, close to where the flooring section meets the transom. Why? Because like previously stated, rot starts at the bottom of the transom and moves up. So if the bolt hole areas are okay, you still could have lower transom rot as well. So drill the test holes there as well. And if everything looks okay, fill in the few drill sample holes and happy boating. Here is what you are looking for when you do those test drills. If the drill shavings comes out dark, wet or even moist, it is rot. If the shavings comes out dry, light colored wood shavings, it is okay. Keep us posted. JMHO!

 

[TomToms]

No Title

Here's a photo, you can see the crack running between the two bolts. You can also see the hole I drilled, it seemed moist to me, and dark brown, but I didn''t have much time, tonight I'll be doing a much more thorough check.

 

[jbcurt00]

I dont think you're going to like what you find.

 

[TomToms]

Alright well lets say i got a rotten transom, Whats the cheapest way to fix it so it holds for 2-3 more years

 

[TomToms]

I have time and the energy to put work in but I am very very limited on cash.

 

[Watermann]

So are those the bottom mounting holes then under the splashwell? Is that water running down the transom or dried resin?

Looks like there's a stop crack hole drilled in the glass. You really should do the testing of the wood and post results before jumping to how do I fix it.

 

[jbcurt00]

I'd like to see the outside top edge of the transom, where the motor hangs and the whole outside transom.

I dont particularly like the joint visible at the top of the pix you posted

 

[TomToms]

Watermann yes, what you see in the top of the picture is the bottom of the splashwell and that's dried resin, not water running through, there never water running down the wall on the inside. That hole you see drilled, is the hole I drilled. I just happened to drill it on the crack. The wood that came out was moist and dark brown.

jbcurt00 I will be going more in depth tonight and I will post more pics including the outside of the transom, I'll also try and get a video of my leaning on the motor to show the current amount of flex. Though when I do jump on the cavitation plate a bit, the entire boat and trailer start bouncing.

 

[Watermann]

Yeah sorry to say that transom is mulch then and will need to be replaced for the boat to be safe for use.