Why does everyone make the whole transom of the same material ??

[tunnels]

The most important part of any transom is the place where the motor is mounted !!
The rest of the transom on either side is there to stop the water from coming inside the boat so why is it necessary to build it from the same material all way across from side to side ??? If a light weight foam or honey comb is used for the sides its still as stiff as before and possibly lighter weight !
The center section only could still be plywood or balsa or a combination of balsa and solid timber even ! but needs to be glass over completely and sealed !! then the laminate for the sides taken all the way across side to side and 4 inch's onto the hull topsides and down onto the hull !!

What part of the transom is the most prone place for holes and letting water get in ? Its normally the center area ! drain hole in the bottom ! splash well holes to let the water out and bolt holes for the motor mounting ! the rest of the transom either side usually never gets holes drill into it or through it !! so why not make the center section of a different material than what the sides are and glass the Centre section separate and completely so water is unable to penetrate to the outer parts each side?

[W2F a V-King]

Because it's easier to make it one piece as opposed to making it out of more than one or more different materials and have it end up as strong ?

You ask questions like a lawyer....you ask no question you don't already have the answer..

Guess it could depend on how the original transom is designed. The transom on most of the Hydrostreams is just a section a little over 3 ft. wide, where as the boat has ( mine anyway V-King ) just a bit under an 8 ft. beam. Transom on a lot of smaller fast boats don't run beam to beam to begin with.

Maybe a beam to beam transom may help keep the rear of that kind of designed boat from twisting or flexing under load, like the lunch box lid idea keeps the lunch box from going out of shape??

Here is a picture of my V-King's transom.. ( don't pay attention to the mocked Styrofoam stringers...not going with that layout ) You can see the transom is a little over 1/3rd the width of the beam.


James H.

[home made tunnel]

Bayliner builds horrible transoms.... So I had to build a better one.

1 piece is for simplicity and strength. I think for 99% of applications, the weight saved to use a different material is nominal / peanuts. The extra cost / work to do it doesn't outweigh the benefits.

Also, most boats concerned with weight on this forum don't have full transoms anyway - Like the above poster showed, performance boat transoms are relatively small anyway.

[tunnels]

Bayliner builds horrible transoms.... So I had to build a better one.

1 piece is for simplicity and strength. I think for 99% of applications, the weight saved to use a different material is nominal / peanuts. The extra cost / work to do it doesn't outweigh the benefits.

Also, most boats concerned with weight on this forum don't have full transoms anyway - Like the above poster showed, performance boat transoms are relatively small anyway.

In that case why not dispense with a core completely and make a solid glass transom ?
Its a oncer and never have to worry for ever more !! AND mix layers of a few layers of corematt amongst the glass laminate to build thickness quicker !! Core matt !!.properly wet out has excellent compression strength for when you bolt the motor back on and wont crush !

[home made tunnel]

In that case why not dispense with a core completely and make a solid glass transom ?
Its a oncer and never have to worry for ever more !! AND mix layers of a few layers of corematt amongst the glass laminate to build thickness quicker !! Core matt !!.properly wet out has excellent compression strength for when you bolt the motor back on and wont crush !

Because plywood is cheaper and has been working for half a century+ when glassed and sealed right. And not all that heavy either. Solid glass is very heavy

[W2F a V-King]

Found an interesting video on the different types of glass, and which one does what.

https://www.youtube.com/watch?v=ioj1YBm6bJY

Might be basic info for some, but 8 minutes of good info for me.

Some of the things mentioned in the video, Tunnels has been saying all along, fiber type and direction laid, etc.............

It's been 25 or so some years since I did any major glass repair, and I didn't have the internet back then and just glassed by the seat of my pants.

It always seemed to work out, never had something I made fall apart, but then I tend to over build stuff. If it looked like 2 layers was enough...I put 3 or 4, etc... No 2" transoms in anything I did, always a minimum of 3" layered plywood with heavy glass between each piece of wood. Strong as heck, but heavy as heck too.

HTH

James

[FMP]

Bayliner builds horrible transoms.... So I had to build a better one.

1 piece is for simplicity and strength. I think for 99% of applications, the weight saved to use a different material is nominal / peanuts. The extra cost / work to do it doesn't outweigh the benefits.

Also, most boats concerned with weight on this forum don't have full transoms anyway - Like the above poster showed, performance boat transoms are relatively small anyway.

Not saying they are all good but I know of Babeliner Arriva that once had an F5 150 on it and now for many yeas an Opti 135. The transom on these have a built in set back of about 10 inches. This boat has been wet from day one and is still good but showing some age. Not the boat in the pic but the same model. It was built fairly well or the pounding it takes year after year would have put that Opti on the bottom.

[blacktruck]

The most important part of any transom is the place where the motor is mounted !!
The rest of the transom on either side is there to stop the water from coming inside the boat so why is it necessary to build it from the same material all way across from side to side ??? If a light weight foam or honey comb is used for the sides its still as stiff as before and possibly lighter weight !
The center section only could still be plywood or balsa or a combination of balsa and solid timber even ! but needs to be glass over completely and sealed !! then the laminate for the sides taken all the way across side to side and 4 inch's onto the hull topsides and down onto the hull !!

What part of the transom is the most prone place for holes and letting water get in ? Its normally the center area ! drain hole in the bottom ! splash well holes to let the water out and bolt holes for the motor mounting ! the rest of the transom either side usually never gets holes drill into it or through it !! so why not make the center section of a different material than what the sides are and glass the Centre section separate and completely so water is unable to penetrate to the outer parts each side?

The most important part is actually the whole transom and how it integrates with the hull. That's why you see uniform transoms, knees and re-enforced braces, supporting the whole transom. Imagine if you had just strength in the part where the engine / engines were mounted? It would break at the weakest point. The leverage on the transom is incredible, many outboards weigh over 500 lbs, multiple engines etc. The transom integrity is the most important part of the boats overall integrity.

Composites are the way to go. Sandwiched cores can be super strong, way beyond wood and lighter. There are different densities and builds for different uses, like these: http://www.gurit.com/Our-Business/Co...Core-Materials

Wood is heavy, rots, soaks water and is not as strong. Advanced foam doesn't absorb water, even if you drilled into it, the cells are tiny, no water penetrates. Way more to a transom then keeping water out.

[blacktruck]

In that case why not dispense with a core completely and make a solid glass transom ?
Its a oncer and never have to worry for ever more !! AND mix layers of a few layers of corematt amongst the glass laminate to build thickness quicker !! Core matt !!.properly wet out has excellent compression strength for when you bolt the motor back on and wont crush !

Sandwich core, lighter, stronger etc.

[GregAdams]

In that case why not dispense with a core completely and make a solid glass transom ?
Its a oncer and never have to worry for ever more !! AND mix layers of a few layers of corematt amongst the glass laminate to build thickness quicker !! Core matt !!.properly wet out has excellent compression strength for when you bolt the motor back on and wont crush !

I wouldn't use coremat in the transom. Compression from the engine bolts coupled with vibration from the engine is not a good combination. Some of you are running solid engine mounts which increases the vibration transmitted to the transom.

Sandwich core, lighter, stronger etc.

Is there a better core material for transoms than plywood? It has a natural vibration dampening ability, and longevity that I haven't found in any other core material. All the problems with plywood come from two sources. Deficiencies during construction, and the holes drilled in it afterwards. Having said that, I don't put cored transoms in my new boats these days.