I am building to 27.5’. I will be building the 4" taller transom similar to what is in the plans at this point. I guess I can always cut it off if I decide to go with the bracket look like Rbob is doing. I have seen some pretty sexy splash wells on tolman skiffs. Will worry about swim platform later.
Brian, let's say for instance I max out the transom weight rating with horsepower. I construct/install some variation of a swim platform. If I go diving and crawl back into the boat over the transom using the swim platform. Will the transom rip off the boat motors and all. Consider I weigh between 220 and 240 depending on what time it is. My soaking wet dive gear likely adds another 100 pounds. Now the transom is overloaded by 340 pounds plus the weight of the swim deck.
Haha ... you weigh less than me!
First, no, you will not rip off the transom. Impact loads on the transom during normal operation exceed that by a long shot - no worries.
That said, my suggested build style for divers is to extend the stringers past the transom far enough to provide a swim platform, and extend the bottom panels and chine flats as well. This effectively lengthens the boat and puts the motor 'on a bracket' (of sorts). The way to lengthen the boat is to space out the lofting stations (equally) from the amidships point aft - check the manuals and study how the loftings change between the base 26' model versus those that are longer (noting that the same thing is done in reverse for shorter than 26 feet). In a nutshell, you divide the extra length by the number of gaps between equally spaced stations, then increase each station separation by that amount. The manuals will illustrate this better than this post.
The reason I like the method above is because it naturally provides flotation for motor and/or weight (you) climbing onto the swim platform. Since the boat is becoming effectively longer as well, this also mediates the aft movement of the CG due to the motors (and you) being behind the transom. This method has already been used on a few Great Alaskans and it works very well.
In your case, you'd effectively lengthen the boat from 27.5 ft to say ... 29 or 29.5 ft long on the water. K. Cannon in Oregon has a 29' 4" GA that already proves this length works well.
Brian