http://www.all-about-houseboats.com/hou ... avits.html

Has anyone seen, used, have knowledge of a towing rig as pictured in the attachment; it is from a houseboat forum & they go slow. We usually cruise at 12+kts. RIB is a Novurania 11.5L X 5.5ft.B, weighs 571 lbs. dry total including 197 lb. 25 hp Yamaha. I plan on using the existing typical Weaver Snapdavits on the swim platform as the pivots, hoist it with a winch or block & tackle & secure it with rigid stand off arms from the towing ladder arms to the stand off arm brackets on the transom plus the hoist cable. Probably attach the winch or block & tackle to one of the aft deck vertical stanchions. I'll get some exact measurements including angles & find a mechanical engineer to do a force analysis so I can check with Weaver & make sure the Snapdavits & standoff brackets will carry the load plus a substantial safe margin. That will be an interesting exercise as the amount of buoyancy at the bow partially supporting the weight will be tricky to determine. I'll have a stout cover fabricated to prevent shipping water underway. I've looked at roll on & typical hoist davits for a heavy RIB - cost substantially more than I paid for the RIB plus quite a lod on the swim platform I would think. There will be an issue berthing the boat. Will have to heave to, lower the boat, raise & secure the ladder & use snap davit rings on the RIB to secure it transversely to the swim platform & then proceed very slowly, as usual anyway, into the marina & berth. Won't be an issue anchoring. Any mech. engineers out there that want to take this on? I'm concerned about it bouncing in the close behind wake & forces that might transfer to the boat & attachments.