Originally Posted by matt167
56 MPH on a 454 BBC? how heavy is that boat?? my faimily used to have a 21' 1973 Starcraft Chieftan cabin cruiser with a 181 CI Chevy 4cyl with a Mercruiser I/O outdrive and in calm water, would turn out 53 MPH on the GPS.
Diffrent pitch props can effectivly change your powerband sort of how a torque converter works
This is a direct drive inboard- so it has a 1:1 transmission (BW Velvet Drive) and a fixed shaft angle. Getting boats to run fast is 20% engine and 80% hull- the more you can get out of the water, the less drag, so the more speed. Outboards and I/O's can trim up the engine/outdrive in order to minimize the running surface... theres no such variable with an inboard... youve gotta make all your gains by adding more power.
Inboard tournament ski boats are built to pull- the term "water tractor" comes to mind. Theyre not built for top speed though- most small block V8 direct drives (not v-drives) top out in the mid 40's. Typical wakeboard speeds are in the 20's, slalom skiing speeds in the 30-36 range, and barefooting in the 38-45 range, so theres little functional reason for them to go faster... but there are some of us who think building up classic inboards with big V8's is a lot of fun. Naturally there are some bragging rights involved, hence my question.
To answer your question, the boat is about 18', and dry weight should be around 2700 lbs with the big block. My guess is that its a few lbs heavier than that due to a soaking wet structure underneath the floor, so its getting rebuilt this year.