Leglicker
22-10-2008, 09:49 PM
Have owned for about 10 years running twin 70 Evinrudes 1988 two stroke ,goes good ,cruise 18knts at 4200 rpm in good conditions pushing about 3000+kg. ( w.o.t 25knts). Looking for more torque to punch in rough conditions + better economy and range.
Think 1x200hp Honda will be the right repower because of economy between 2000 to 4000rpm and flat torque band.
Boat is glass with reverse chine to flat keel and known as Hobson Solocraft (NW coast Tasmanian fishing boat)
Question: Given the hull efficiency under twin 70's what horsepower would be currently developing at 4200rpm and if repowered by 200hp Honda only dragging one gearbox what HP or rpm would I need to run at to achieve 18knt cruise and how much higher cruise could I expect while staying under 4000rpm?
This is my first thread, just joined last night. User name was meant to be Legliker, if no offence will leave as is. Its a long story but many years ago I did say I liked legs rather than outboards. I don't anymore! :o
Any thoughts on my repower conundrum will be most appreciated.
Think 1x200hp Honda will be the right repower because of economy between 2000 to 4000rpm and flat torque band.
Boat is glass with reverse chine to flat keel and known as Hobson Solocraft (NW coast Tasmanian fishing boat)
Question: Given the hull efficiency under twin 70's what horsepower would be currently developing at 4200rpm and if repowered by 200hp Honda only dragging one gearbox what HP or rpm would I need to run at to achieve 18knt cruise and how much higher cruise could I expect while staying under 4000rpm?
This is my first thread, just joined last night. User name was meant to be Legliker, if no offence will leave as is. Its a long story but many years ago I did say I liked legs rather than outboards. I don't anymore! :o
Any thoughts on my repower conundrum will be most appreciated.