- Jul 10, 2020
- 152
- Boat Info
- 1981 310 Vanguard Express
- Engines
- Twin Mercruiser 6.2 MPI Horizon FWC inboards
I had 3 blade, 14x21 pitch (yes really) props last season; they came with the boat. The engine topped out just under 4,000rpm WOT, this is below what I'd expect (engines want 4,500-4,800rpm.)
I found a spare pair of 4 blade 17x14 props on the boat, in tired condition. I've cleaned them up and polished them and can get them balanced easily. They look great now.
Question is, am I going to load the engine less with 4 blade 17" diameter 14" pitch props or with the 3 blade, 14" diameter, 21" pitch props that were on it? It's not just an academic question: there's a nick in the edge of one of the three blade props, so I'd have to get that fixed anyway. If I swap them out, I'll save myself a propellor refurb bill.
Seems very hard to find calculations for this stuff. I tried one of those online prop analysis things but nobody got back to me. And the prior owner has no memory of what he did with props (though he is a lovely old guy who is still in touch with me and very helpful every now and again.)
I found a spare pair of 4 blade 17x14 props on the boat, in tired condition. I've cleaned them up and polished them and can get them balanced easily. They look great now.
Question is, am I going to load the engine less with 4 blade 17" diameter 14" pitch props or with the 3 blade, 14" diameter, 21" pitch props that were on it? It's not just an academic question: there's a nick in the edge of one of the three blade props, so I'd have to get that fixed anyway. If I swap them out, I'll save myself a propellor refurb bill.
Seems very hard to find calculations for this stuff. I tried one of those online prop analysis things but nobody got back to me. And the prior owner has no memory of what he did with props (though he is a lovely old guy who is still in touch with me and very helpful every now and again.)