how thick should transoms be?

[arty007]

hey everyone.. im asking about the thickness of the transom..on my 19 ft bowrider 1978 sterndrive .. ive drilled holes at the bottom of my transom and i think i got lucky (or not) wood chips came out dry, but! when i measured to see how thick it was its like 5/8 maybe 3/4 i measured on top just wondering if i should leave it or do i need to replace with thicker plys? looks like they did the transom before, because only the transom has a fresh coat of what looks like black paint on it im aabout to start on my stringers and need to be reasured if its going to be okay with whats on there i guess.. sorry for all the stupid questions...

 

[AZSenza]

Re: how thick should transoms be?

Well...only the area where the drive bolts up is the thick part, it needs to be 1 1/2 -2" thick for several inches past the drive. The rest can be an inch or so but if your doing it, Id have the whole thing 2". I'm betting you drilled into the thin area below or away from the mount.

 

[arty007]

Re: how thick should transoms be?

Well...only the area where the drive bolts up is the thick part, it needs to be 1 1/2 -2" thick for several inches past the drive. The rest can be an inch or so but if your doing it, Id have the whole thing 2". I'm betting you drilled into the thin area below or away from the mount.

yup!!i drilled below the mount and on the corners about 2 inches from the hull, should i drill more what else can i do to make sure theres no rot? there is another piece of 3/4 or 1 inch ply in the center maybe about 20 by 20in

 

[erikgreen]

Re: how thick should transoms be?

It's usually safe to match the original manufacturer's thickness with a good quality ply, unless they had something better there like honeycomb plastic, which wouldn't rot.

There's a certain thickness needed for I/O drives because of the way they mount, if you're going to change your transom thickness check out what your drive needs.

There are specified transom thicknesses in ABYC (American Boat and Yacht Council) standards for specific outboard horsepower.. it's roughly 1.5 inches for a 150 horse, 2.5 for a 250.

Erik

 

[arty007]

Re: how thick should transoms be?

thanks for the info ericgreen..

 

[APPALOOSA2]

Re: how thick should transoms be?

Total transom thickness MUST be 2"-2 1/8" for the Mercruiser outdrive.

 

[drewmitch44]

Re: how thick should transoms be?

How can Ya tell?

 

[special_kaye]

Re: how thick should transoms be?

It's usually safe to match the original manufacturer's thickness with a good quality ply, unless they had something better there like honeycomb plastic, which wouldn't rot.

There's a certain thickness needed for I/O drives because of the way they mount, if you're going to change your transom thickness check out what your drive needs.

There are specified transom thicknesses in ABYC (American Boat and Yacht Council) standards for specific outboard horsepower.. it's roughly 1.5 inches for a 150 horse, 2.5 for a 250.

Erik

So, as I'm currently replacing my transom, should I make it thicker? The original is 1.5 nches and the boat is rated for a 235hp. I took a 200 off and will run a 150SS but should I go ahead and make the transom thicker just to be within recommendations? Yes, I know "it's my boat and I can play with it how I like," but I'm looking for opinions here. Cost wise, it'll be very little add on and I'm not worried about that. Safety, yeah, it'd probably be better and won't add more weight than a case of beer....
Opinions?

EDIT: Just remeasured old transom location, I've got 99% of the old wood out, and it's only 1.25 inches. I just eyeballed it before. So, yes, I'm now going to make it 2.5 inches. Because I can.

 

[Robert D]

Re: how thick should transoms be?

The extra thickness on a transom for an outboard is a small increase in price, for the big increase in piece of mind and probably safety. However, if you go all out and really make everything strong, the cost goes up quite a bit. I'm finishing up my 1972 Reinell, changed transom from a 20" to a 25 " for a certain 150 hp motor I have, and decided 3 inches was so much overkill....but what the hell, it gives me a lot of piece of mind. I then looked at this awesome transom that I could hang a couple 250's off of, and started to think like an engineer, and beef up everything that may get torqued. A transom may be bulletprooof, but what about everything it connects to? The back 4 feet of the hull, the stringers, knee braces, splashwell, etc. I use all epoxy, and I will admit I've used double what was needed....but I sure feel good about it! Just had elbow surgery last Friday, so project on hold for a couple weeks :-( I say as long as you are doing more than the factory, you are probably improving things. Just make sure if beefing it up for something bigger than the factory took into account, you address the above area's as well. Make sure you get a couple second opinions from builders as well, if possible. I'm fortunate, I have a boat factory a couple miles away, and I routinely do business with them....and have got a lot of free advice, design suggestions, etc.