I have been chomping at the bit to respond. I am twixt between you are just playing with the forum knowing you are tweaking those of us who actually utilize the subject as a reality or you truly believe your prognostications.(Said with good humor
Your 31 foot Camano is one of the most suited boats for our part of the world. We don't have any number of them as residents, as I mentioned in prior post. That said, they are a pure Southeast Alaska candidate for near perfect.
The Camano as well, is the perfect candidate for a stern mounted outboard.
I will give you that OB. It is the 9.9 Hi-thrust Yamaha. These are geared in such a combination to equal the thrust of a 18 hp standard OB of comparable size. This is the motor I had on our last boat, a 28 foot 19,000# converted harbor tug. We pushed the boat at 4.5 Knts by GPS as an average, when we used it to bring ourselves home and often during short moves in the fishing grounds.
The data I am giving forum is actual data, not subject to conjecture or maybe so. It is fact. Not only that, in our local fleet, the 9.9 Yamaha is the most popular motor for the same use secondary to a trolling motor.
We Alaskans all calculate that at some point in time we will require the use of this motor as our insurance at time of need.
What I am attempting to project, is until I read the forum on the question, with as many years under my life vest on the water, had the death of challenge to the use of the OB become as it has here. Now, I understand the straw-man, "The size of the boat in relation to the size of the OB being considered-But"."Water conditions- But" "Will be subject to Pooping-But"
In the case of your particular boat, the perfect candidate for such an application is ignore the potential of the safety factor in having installed one Visit our area of the world, break down and when a local comes alongside to assist, I would not be surprised to have that person quietly suggest that you consider such an investment as he gives you a helping hand. We do that here, all it takes is getting our attention. (Another story- later regarding visiting boats from America, passing by broke down mariners)
As to the argument regarding a required high horse powered engines for 35-40 foot boats. It seems reasonable that a boat in that range will have a sufficient size auxiliary boat on-board with a horse powered engine sufficient to either tie along side or tow the boat into a safe harbor. I don't recall seeing boats of the size with OB's on the stern unless like the photo in an above post depicted.
There are a couple locally I know of- 30-40 footers who have removed the inboards and replaced with big OB 150-300 hp. The fuel efficiency of the new larger OB's meet the consumption of the original inboards with ease of installation and benefit of obtaining added space. Even there, in one case the large OB is a 300 plus hp. the owner included a 25 hp Honda as an auxiliary!
I want to add another remark that you made Ron. As it is apparent that you have not undertaken or had an opportunity to operate under a "Git-a-Home OB application, allow me to assure you that you can steer a displacement hull under OB power with the vessel's rudder. You will suffer control issues in the confinement of the harbor when you arrive, however, at that time one is required to physically use the tiller of the OB as you will be shifting the throttle/gear shift as required. During the voyage TO the harbor you will be quite able to maneuver the boat. Trust me, I have done it on one long trip back on the OB and twice in short shots to arrive at a secure anchorage.
I am presently in the learning stage of how to post a photo in a blog site.When I am able I will submit a photo of the boat where all of this exercise was accomplished.
27' Marben pocket trawler
"I've learned that you cannot make someone love you. All you can do is stalk them and hope they panic and give in."