Prop Advice needed
OK, second post on this topic so i hope no one gets bored...
We have a Ribcraft 6.3 with a 150 Opti on, that regularly carries 10 diver plus kit plus 2 crew. Total load probably in the region of 1300 kgs.
At the moment it is turning a 3-blade vegance, 17P. Loaded it is VERY slow to plane, and tops out at 4800 rpm. Manual says WOT 5600-5750. At 5600 rpm (3 up plus a bit of kit) we get 38 knots.
Interesting part is....
One mariner dealer said "change to a 15p prop, 13 is WAY to low" he actually said the engine would explode, but i think he was joking.
Another dealer said "go to a 15p, 4 or 5 blade prop, to get better pick up"
I think the prop diameter is 13.5, so my logic is to get a 14.5 x 15p 4 or 5 blade prop as well....
Except, steel developements said, "there is no 13.5d vengance, it must be a 14.5, you need a 15.5 x 13p, and they only come in the 3 blade flavour, 15p won't give you enogh extra rpm" The trouble is, this is different to what they said the last time i rang them with the same numbers!
I then rang Ribcraft to ask their advice, and they said they couldn't comment on a specific boat, and to go and try it. When i said i had, and gave them the numbers they said i needed to get a different prop...(doh!)
So.... HELP! Does anyone have any opinions? I don't care if it's guesswork, calcualtion or came from your tea leaves.