Transom through bolts... type, sealing question.

[muskyhunter1978]

As some of you guys know, I'm knee deep at the moment on a transom resto on a Starcraft boat. So far so good, everything is going beautifully. I'm taking stock of the hardware I need to replace as I will not use any of the old stuff when I put this thing back together. Looking at replacement bolts that go through the transom, I believe they are called truss head bolts. I'm thinking of using star head instead of philips because well... I hate anything philips head and avoid them if I can. I already found a place to order these bolts in I believe 304 SS. Is my assumption correct in that the truss head is the correct type? Anything better?

As for the second question. What is the best way to ensure these seal? I have heard/read that using a nylone washer is a good idea to one help seal, but two, to ensure a bit of a separation of the SS bolt and the aluminum. Assuming this is more of a concern in salt environments than fresh, but if I can do it for .10 a washer... why not? Do you recommend applying sealant to the bolt/hole when installing? The original bolts had no washers and I did not detect any sealant either.

Thanks fellas.

 

[mbullen]

Personally, I use 316 SS.
Bolt Depot is usually my first stop based on pricing, but there are dozens of other resources.
I don't use nylon for separation but I know folks that do. Can't hurt, but I've chosen not to go that far.
My boats are freshwater trailer queens and I feel that the large footprint of aluminum is more than enough to dissipate the galvanic activity of the small footprint of the SS.
316 SS is very close on the ionic transfer chart, anyway.
As for sealing, there are two instances for concern: The sealing of the new transom wood and the sealing of the hardware in external holes.
For the wood, I make sure to continue whatever sealing process was used on the surface of the wood into the new through-holes, sealing the internal passages.
For the external hardware, I favor 3M 5200. (5200 is considered permanent, 4200 is considered semi-permanent).

Ultimately, you'll find many opinions, and honestly, most will be valid. These are just my routines and after more than several restos, I feel I've had very good measures of success.

 

[muskyhunter1978]

Personally, I use 316 SS.
Bolt Depot is usually my first stop based on pricing, but there are dozens of other resources.
I don't use nylon for separation but I know folks that do. Can't hurt, but I've chosen not to go that far.
My boats are freshwater trailer queens and I feel that the large footprint of aluminum is more than enough to dissipate the galvanic activity of the small footprint of the SS.
316 SS is very close on the ionic transfer chart, anyway.
As for sealing, there are two instances for concern: The sealing of the new transom wood and the sealing of the hardware in external holes.
For the wood, I make sure to continue whatever sealing process was used on the surface of the wood into the new through-holes, sealing the internal passages.
For the external hardware, I favor 3M 5200. (5200 is considered permanent, 4200 is considered semi-permanent).

Ultimately, you'll find many opinions, and honestly, most will be valid. These are just my routines and after more than several restos, I feel I've had very good measures of success.

Thats exactly the type of information I was looking for. Thank you.

My boats too are fresh water only and trailered so I'm not overly concerned about the galvanic issues. I will look for the 316 SS bolts however.

My wood core build was to glue up the layers, then dropped it in the boat to get my holes drilled. I then pulled the wood back out and redrilled each hold 1/8' larger than they needed to be. Then I coated the wood in epoxy resin and filled each drill hole completely with epoxy. Then I dropped it back in the boat again and redrilled through the epoxy center of the holes with the 1/4" bit again. Essentially all the wholes are sealed with epoxy. I was planning on gooping sealer on the boats during install just to hear confirmation on it and if the nylon washers are a good idea.

Thanks again!

 

[thill]

5200 on engine bolt holes? Ouch. I've had to remove engines that had 4200 or 5200, and the bond is so tenacious that it sometimes pulls the skin of the boat off with the engine.

Personally, I use 3M marine silicone applied inside, outside and on the bolt itself. You want enough that the entire area is thoroughly filled in, but not so much that it's blobbing all down the back of the boat.

A trick I've used at times is to tighten up the bolts "most of the way" but not fully torqued down. Then come back in a couple of days and torque it fully. Supposedly, this allows the silicone to firm up, and then when you torque it fully, it acts as a gasket. Supposedly, this is good for aluminum boats to isolate parts.

But generally, I coat everything, torque it down, wipe excess as needed and call it a day. No issues either way, but I strongly recommend that you use something. If not, your transom is going to take on some water and possibly even leak into the boat itself.

 

[muskyhunter1978]

I have both 4200 and 5200 on hand, though I never had a need for the 5200 at this point. A trick with 4200 and I'd imagine it works with 5200 as well, is to take a heat gun and heat it. It softens right up and you can remove it fairly easily.

 

[flatheadsteve]

I've always used marine grade silicone on transom bolts. Only place I've used 5200 is on seats that have stripped out threads and mounting a transducer board to the transom. 5200 is permanent the only way I know to remove is with an adhesive remover that 3m sells and even then it's not easy.

 

[Zip]

Boatlife caulk. Useful for if you ever need to remove motor in the future.

 

[mbullen]

5200 on engine bolt holes? Ouch. I've had to remove engines that had 4200 or 5200, and the bond is so tenacious that it sometimes pulls the skin of the boat off with the engine.

Personally, I use 3M marine silicone applied inside, outside and on the bolt itself. You want enough that the entire area is thoroughly filled in, but not so much that it's blobbing all down the back of the boat.

A trick I've used at times is to tighten up the bolts "most of the way" but not fully torqued down. Then come back in a couple of days and torque it fully. Supposedly, this allows the silicone to firm up, and then when you torque it fully, it acts as a gasket. Supposedly, this is good for aluminum boats to isolate parts.

But generally, I coat everything, torque it down, wipe excess as needed and call it a day. No issues either way, but I strongly recommend that you use something. If not, your transom is going to take on some water and possibly even leak into the boat itself.

Transom bolts are not engine bolts.

(and my motors clamp on)

 

[Sea Antsy]

Boatlife caulk. Useful for if you ever need to remove motor in the future.

Oh YEA.. I second the BOATLIFE BOAT CAULK.. the toothpaste size tube lasts for yrs,not like the 5200 "ONE SHOT" tubes
and it is removable and does not mould

 

[thill]

Transom bolts are not engine bolts.

(and my motors clamp on)

DUHHH... Thanks for the correction. Yes, 4200 or 5200. Sorry, didn't read carefully.