So...most will know I love a good prop post. Would like to consider myself pretty decent on this subject but as we all know, the world of prop selection is a delicate and black art for the most part. Here goes
I’m delighted to say I’ve just bought a new (and 3rd boat. God help me) she is an astounding fletcher 19 GTO cuddy model. Most in the North American area won’t be aware of these. In Europe fletchers are well known for having that almost impossible ability to be quick hulls but also so capable in the rough stuff too. Normally it’s a compromise either way. Anyway. She has moderate low HP with her 115 efi mariner outboard and a fairly hefty deep v hull to deal with.
Mad as it seems but the guy I bought it off had the engine fitted new in 2016 and didn’t hold back. He installed the smart craft full fit out and an almost crazy tempest plus 14 and 3/4 x 19” prop (it’s the command thrust so big gearcase fitting like the big V6 or Alpha one).
Now this is a pretty serious prop for such a small engine and heavy boat. But she performs so well with it. Lots of lift and manages an amazing 43 gps. The only issue is that this engine is rated at 5000-6000 rpm. The boat will manage 43 mph but it will be just a little over the 6000 rpm at that. Not enough to limit the rpm or alarm but must be close.
Here is the issue. The tempest plus seems to be a little large on the diameter side, compared to the average prop of its pitch. It’s nearly 15” diameter at a 19”. I’m hoping I can go to a 21” laser or similar (at under 14” diameter) and she will still pull around 5600-5700 rpm but still manage to plane fairly well. Has anyone any experience going from a big diameter prop to a smaller and a couple inch pitch difference. I’m well aware that the go to answer is 400 rpm for every 2 inch change in pitch but this tempest is such a diameter that it must effect things a little. It’s that big that it will rotate below the line of the skeg of the gearcase. I can’t get a trim anode on it either to offset the horrendous torque steer.
Thanks for any opinions.
allan.
I’m delighted to say I’ve just bought a new (and 3rd boat. God help me) she is an astounding fletcher 19 GTO cuddy model. Most in the North American area won’t be aware of these. In Europe fletchers are well known for having that almost impossible ability to be quick hulls but also so capable in the rough stuff too. Normally it’s a compromise either way. Anyway. She has moderate low HP with her 115 efi mariner outboard and a fairly hefty deep v hull to deal with.
Mad as it seems but the guy I bought it off had the engine fitted new in 2016 and didn’t hold back. He installed the smart craft full fit out and an almost crazy tempest plus 14 and 3/4 x 19” prop (it’s the command thrust so big gearcase fitting like the big V6 or Alpha one).
Now this is a pretty serious prop for such a small engine and heavy boat. But she performs so well with it. Lots of lift and manages an amazing 43 gps. The only issue is that this engine is rated at 5000-6000 rpm. The boat will manage 43 mph but it will be just a little over the 6000 rpm at that. Not enough to limit the rpm or alarm but must be close.
Here is the issue. The tempest plus seems to be a little large on the diameter side, compared to the average prop of its pitch. It’s nearly 15” diameter at a 19”. I’m hoping I can go to a 21” laser or similar (at under 14” diameter) and she will still pull around 5600-5700 rpm but still manage to plane fairly well. Has anyone any experience going from a big diameter prop to a smaller and a couple inch pitch difference. I’m well aware that the go to answer is 400 rpm for every 2 inch change in pitch but this tempest is such a diameter that it must effect things a little. It’s that big that it will rotate below the line of the skeg of the gearcase. I can’t get a trim anode on it either to offset the horrendous torque steer.
Thanks for any opinions.
allan.
