Folks, I'm really appreciating the discussions. My thanks for the inputs!
I am finding this a bit like drinking from a fire hose (there are a bunch of very knowledgeable folks on this forum) - so I think I'll try to respond to the key topics instead of each post.
Mounting strength:
I'm still absorbing the suggestions for strengthening the deck mount arrangement. Part of me says to trust the NA that I asked for advise; part of me says stronger is better. Aesthetics come into play here - the mount area is overhead - where one walks under it each time you go to the side boarding gate. I have the feeling that gussets tend to look like headbangers... the admiral would not like that.
Dink requirements:
When considering this originally, I made some estimates:
The current Dink is an Achilies SPD4FL w a 8HP 2 stroke Evenrude. All in with gas, some misc stuff (small ice chest, radio, seat etc) I estimate it to be 200-250 lbs total.
The Achillies is removable floor board dink. I'd like to have a RIB. But in any case the dink will never be longer than about 10ft - that's all the space there is on the FB for the dink.
I looked up several RIBs and 15hp 4 stroke OBs and estimate that the package would be <less than 350lbs.
Thus I arbitrarily picked 500lbs static load as the "future proof" design goal and figured if I can get more margin for not much cost increase, I'd do that. Hence the 1000lb value as a stretch target.
Pipe Cranes: Due to the fixed radial reach nature of the pipe cranes, I'm thinking I have to stick to my idea of a lifting boom. I need to be able to pick up stuff from a couple of locations that are not equidistant from the crane mount location. There are some motivating reasons for this that would take a bit to explain - if anyone is interested, I can try to add that info tonight or maybe tomorrow.