Dear List, The dink concept we've landed on has 4 crew sitting motorcycle style on the tunnel cushion, driver forward (cozy - sort of DisneyWorld, but dry). We'll use a Yamaha which allows us to tiller steer when getting off the beach in surf, and use the remote once settled. The soles are above the waterline, so the dink self-drains fast/easily when empty. Lots of topside flair - we really want the ride to be as dry as possible. The topsides are flexible, and covered with 1.5" Gunnel Guard - hopefully enough impact absorbtion to protect our mothership's 1.2mm thick skins. Actually the whole boat will be somewhat flexible as the skins are only about 3mm thick - only the soles are cored. The hulls are entirely sealed below soles, with sealed bulkheads fore/aft. So inherent buoyancy is very high, even if holed. We'll work out a canopy rig and other details so that the tender will also serve as our raft. We may add a facility for flooding a ballast tank under each sole to increase stability should it ever be used as a raft in severe conditions (not too likely for a cat, where the raft case is most likely catastrophic fire). It's interesting that even with the volume occupied by the tunnel, the interior volume is almost double that of an equivalent rib because so much space is consumed by the tubes. The bare boat weighs only 132 lbs (compared to Avon 3.41 RIB as bare boat 180 lbs), because it is constructed from Kevlar unis, using tension panel design. Rigged boat adds 125# for 25HP Yamaha, 15# for steering system, 80# lbs for guess of 10 USgal of fuel and bladder tanks. So before crew and stuff the "power-away" weight is up to 369 lbs. How long is a piece of string? I have the same sort of question regarding how much fuel capacity we need. The 90% design case I think is driver + one passenger, plus dive gear for two. That brings total loaded DSPL up to 788 lbs. This would represent maybe 90% of usage. If venturing out where engine meltdown puts us at risk, we'll carry a 38 lb backup 3.5HP. The 10% design case is 4 people + their dive gear. Total loaded DSPL around 1300 lbs. In this case we assume the dink stays in waters still safe if lose the engine. Our draft dink design is 12.4 ft LOA, just to give a ballpark size. Fuel economy should be better than equivalent RIB when planing, but for estimating we'll just assume a 12-ft RIB or good hard dink, 25HP. Our thinking on fuel capacity was to build in under the soles tanks enough for the worst case, so we never have to fill up interior space with jerry jugs. I see two cases then: 1) two crew & dive gear - what is max range we would like to have in fast planing conditions? 2) four crew & dive gear - how much fuel needed to do a 20 mile round trip with good safety reserve (e.g., return is upwind and it blows up)? Any opinions or ideas on max desired range and likely fuel consumption? Cheers, Steve ------------------------------------------------ Stephen C. Darden Email: darden@xtra.co.nz Adagio Marine Ltd. Fax: 649/4037-213 P.O. Box 161 Voice: 649/4037-801 Russell NEW ZEALAND