The Boating Forum - what is the prefered shaft length in constructing a new boat?

I am working on a boat that has an enclosed transom and will soon be making a floatation bracket for a single engine (250hp to 300hp). The setback of the bracket will be about 30". I will have the flexibility to mount the bracket at any height I need to. I was wondering what the pros and cons are in using either a 25" or 30" shaft with the bracket mounted appropriately.

I am working on a boat that has an enclosed transom and will soon be making a floatation bracket for a single engine (250hp to 300hp). The setback of the bracket will be about 30". I will have the flexibility to mount the bracket at any height I need to. I was wondering what the pros and cons are in using either a 25" or 30" shaft with the bracket mounted appropriately.
Out of the water? I build floatation brackets out of glass and have never felt the need to use more then a 25 inch engine. I fished my last single 250 hp full floatation bracket in the breakers of the local inlet for stripers and it still amazed me that the waves would smash against the transom and the engine would raise up and away from the wave.

The only con to a 30" shaft is resale in my opinion. Most boats are setup for 25". Some will argue weight but the difference is negligible. I would prefer a 30" because it makes me unhappy to see the motor get dunked to the cowling when drifting or trolling in a following sea.

Just thought of another possible con to a 30" shaft. If you already have the bracket and you are just talking about mounting the entire assembly 5" higher you will loose some of the floatation benefits (assuming it is a floatation bracket).

Since the flotation bracket is being custom made (out of aluminum), should I leave the bracket lower to allow for a 25" shaft to be installed on it (at a later date) but also have the mounting "lip" raised up 5" for a 30" shaft? It then could be cut down it one ever wanted to install a 25" shaft motor. Or is this not practical?

Does a 25" or 30" shaft (mounted at the proper height) make the boat ride any differently?

Still don't know which size shaft would be the best use. I don't plan on reselling the boat for a long time, and per the reply, I hear the weight difference is negligible.

I would think it would depend on the size of your boat, the deadrise angle, and the draft of the boat, whether single or twin. I f single, deep V, and deep draft you may have to use a 30 inch shaft. I think leaving the mounting plate high is a good solution just make sure it is knee braced down to the bracket to provide support for the extra height. They can always be cut down with the plate if necessary.

I went with a 30" so the powerhead would be more out of the water in rough inlets. No cons from my view.