22 sea sport transom modification and swim platform

[Bajamatic]

I'm in the process of acquiring this vessel and have some questions about what I can do to the transom to increase acres to the swim platform. I've read a handful of related posts and have a few questions that I hope can be answered here.

My goal is the replace the swims platform with a larger area as well as to add easier access over the transom as this is primarily a dive boat.

Reading your opinions, it seems that by lowering the transom I am increasing the chances of swamping the boat from the stern. Logical. This boat is an I/o and I was thinking about adding two access doors to either side of the engine and keeping the center of the transom intact. The cutouts would be about 2 feet wide. Am I asking for trouble here? Seems like this modification would only carry a moderate amount of increased risk, if any, of taking water over the stern.

If I do this, am I risking the structural integrity of the hull? Would I need to keep any portion of the transom intact at the corners to maintain stiffness or is that much more about the stringers below the deck?

Is the a good first-time project (I consider myself very adept at building and my partner in the endeavor is an architect)?

Finally, I've read a lot in support of plywood layers as a good way to go for the swim platform. But I'd like this extended swim platform to look and feel more like an extension of the hull. Is plywood still the recommended base material?

[tech_support]

The cutouts would be about 2 feet wide. Am I asking for trouble here? Seems like this modification would only carry a moderate amount of increased risk, if any, of taking water over the stern.

you can put in doors and mitigate risk of swamping. BUT you have to beef of the transom around the doors.

Finally, I've read a lot in support of plywood layers as a good way to go for the swim platform. But I'd like this extended swim platform to look and feel more like an extension of the hull. Is plywood still the recommended base material?

could you please post a picture of what your want to do?

[Bajamatic]

Original Layout:



Mod Concept:



door example:

[tech_support]

Its certainly possible, but it should be designed right (a lot of time). Im afraid we cannot give you much more than ideas on how to do it. The challenge is to replace the stiffness lost by having the single large piece of transom core that spans the transom and carries loads to the sides.

[peter-curacao]

Its certainly possible, but it should be designed right (a lot of time). Im afraid we cannot give you much more than ideas on how to do it. The challenge is to replace the stiffness lost by having the single large piece of transom core that spans the transom and carries loads to the sides.

I know I'm out of my league here still I make this remark Does he really has to beef up his transom that much? It's an I/O not a full outboard, I probably am wrong but I always was in the presumption there was less stress on the transom with an I/O because of the stringer mounted engine block.

[tech_support]

It depends how its set up, but most i/o's push on the transom unless there is a thrustbearing on a frame somewhere.

[jacquesmm]

Joel is correct, in an I/O, the thrust of the engine is on the transom.

[peter-curacao]

Joel is correct, in an I/O, the thrust of the engine is on the transom.

Never to old to learn!
Is it as much as with a regular outboard?

[tech_support]

The pushing forces will be the same, but the I/O doesn't have the same weight so you don't get much of the leveraged bouncing while on a trailer. Im sure the max loads put on an i/o transom would be lower than an outboard only for this reason, but I would not remove any scantlings

If you really wanted to avoid beefing up the transom, it may be possible to put a thrust bearing somewhere along the drivetrain, Im almost certain I have seen that setup before.