I have an 1972 Islander 36 with a Perkins 4107 and Borg Werner gearbox with a 1 to 1 gear ratio (no reduction gear). Is this common on other Islanders with a Perkins diesel - that is, a shaft that turns at the same speed as the engine? As a result, I have to use a very small prop.
Islander 36 transmission gearing
- Thread starter Bill Crysler
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Bill, I don't know if it is common
but it is dumb. You can only go about 7 kts. One inch of pitch at 1 thousand rpm equals one knot theoretical so a 7 inch pitch prop at 1 thousand rpm would come close to the spped you need if the diameter and blade area ratio were right. I turn a 13x15 three blade with a 3:1 reduction gear and a ten horse volvo to push my I30
but it is dumb. You can only go about 7 kts. One inch of pitch at 1 thousand rpm equals one knot theoretical so a 7 inch pitch prop at 1 thousand rpm would come close to the spped you need if the diameter and blade area ratio were right. I turn a 13x15 three blade with a 3:1 reduction gear and a ten horse volvo to push my I30
Transmission reduction
Bill, Your engine and transmission are miss-matched. You should have about a 2.5:1 reduction ratio for your boat/engine combination. Steve S/V Aurelia
Bill, Your engine and transmission are miss-matched. You should have about a 2.5:1 reduction ratio for your boat/engine combination. Steve S/V Aurelia
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