Dinghy weight on deck over stern sundeck

[Matchmaker]

We have 41’ Symbol Sundeck trawler that originally had a crane mounted for storing the dinghy on the deck over our rear G&T deck. I have had no luck finding information on what weight I can carry up there and am looking for advice. The “roof” is aluminum sheet on 3x2 aluminum tube and the supporting posts are 4x4 aluminum tubes. I am about 200lbs and can walk around up there with no deflection in the aluminum panels. It is pretty much rock solid. I am looking to add a crane and purchase a new dinghy so have some flexibility in what weight I can work with. A 10-11 foot dinghy seems to weigh from 350-750 lbs depending on options/engines. Anybody out there with advice?

 

[sunchaser]

Weight aloft affects stability. Quite simply, think moment arm. 500 lbs 10’ above the CG requires 5,000 lbs 1’ below the CG to maintain the same resistance to roll.

In the offshore work I’ve done with some very experienced sailors and cruisers it is amazing the efforts we went to in reducing weight aloft whether on sail or power boats. Country kitchens, dinghies, anchors, chain, self furling rig, FB tables and chairs, mini bars etc. got moved or tossed.

Some years ago when considering a new build the designers showed some interesting stability data regarding weight aloft allowances for Stidd chairs, Steel Head cranes, etc. it was an eye opener as to effects on sea worthiness.

Bottom line, lots of dinghies are successfully placed on the stern. Alaska Seduction on this site detailed a wonderful stern setup he did a few years ago on a similar vessel.