Propellers, turning in or out
11-11-2012 | 08:43 AM
#1
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From: Bedford & Wolfeboro, NH
Propellers, turning in or out
There's so may opinions on this, and it seems different for every hull design . .
I'd like to know which direction is the best for the Magnum 27.
My boat has two Volvo 280 drives with nose cones, raised 2" over the stock location. When I had them rebuilt we set them up for a specific direction of rotation, and it's now time to install them on the boat.
Engines are 383 SBC close to 475 HP, yet to be dynoed and tuned. The present plan is to work with Hale Propellers in CT. They did Geo's 100+ mph 18' Donzi and the owner there also has a Magnum 27.
Seems as though this has been discussed here before, but I can't find the thread.
Mario L.
I'd like to know which direction is the best for the Magnum 27.
My boat has two Volvo 280 drives with nose cones, raised 2" over the stock location. When I had them rebuilt we set them up for a specific direction of rotation, and it's now time to install them on the boat.
Engines are 383 SBC close to 475 HP, yet to be dynoed and tuned. The present plan is to work with Hale Propellers in CT. They did Geo's 100+ mph 18' Donzi and the owner there also has a Magnum 27.
Seems as though this has been discussed here before, but I can't find the thread.
Mario L.
11-11-2012 | 02:51 PM
#2
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Joined: Dec 2003
Posts: 3,496
Likes: 63
From: NewBaltimore Mi
There's so may opinions on this, and it seems different for every hull design . .
I'd like to know which direction is the best for the Magnum 27.
My boat has two Volvo 280 drives with nose cones, raised 2" over the stock location. When I had them rebuilt we set them up for a specific direction of rotation, and it's now time to install them on the boat.
Engines are 383 SBC close to 475 HP, yet to be dynoed and tuned. The present plan is to work with Hale Propellers in CT. They did Geo's 100+ mph 18' Donzi and the owner there also has a Magnum 27.
Seems as though this has been discussed here before, but I can't find the thread.
Mario L.
I'd like to know which direction is the best for the Magnum 27.
My boat has two Volvo 280 drives with nose cones, raised 2" over the stock location. When I had them rebuilt we set them up for a specific direction of rotation, and it's now time to install them on the boat.
Engines are 383 SBC close to 475 HP, yet to be dynoed and tuned. The present plan is to work with Hale Propellers in CT. They did Geo's 100+ mph 18' Donzi and the owner there also has a Magnum 27.
Seems as though this has been discussed here before, but I can't find the thread.
Mario L.
11-13-2012 | 08:13 AM
#3
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Joined: Oct 2009
Posts: 352
Likes: 3
From: LI, NY
Mario,
Its hard for me to say since you have volvo's... but with my bravo's turning in made a big, big difference. (bravo1 4blades) I raised propshaft at least 3"over trs setup. Better out of the hole, much better tracking and general feel. I think the more you raise the X the more you want to eliminate certain stern lift properties of the propellers. Turning in is supposed to anchor the stern more (less stern lift) The tough part is you say 2" above factory but I'm sure that from 1969 to 1979 they raised the X. But I really cant speak to volvo's and how they might act different than merc as you raise them. Most of my detail pics are on my home computer which still has no internet but my prop shafts are just higher than the bottom keel. If I turn a blade perpendicular to the bottom I get a good 2 1/2" of blade tip / transom overlap.
I think 2"up is still pretty conservative and if you run 3blade props which create less sternlift vs 4blades I would probably turn out unless you find someone with your setup to tell you otherwise.
- Marshall
Its hard for me to say since you have volvo's... but with my bravo's turning in made a big, big difference. (bravo1 4blades) I raised propshaft at least 3"over trs setup. Better out of the hole, much better tracking and general feel. I think the more you raise the X the more you want to eliminate certain stern lift properties of the propellers. Turning in is supposed to anchor the stern more (less stern lift) The tough part is you say 2" above factory but I'm sure that from 1969 to 1979 they raised the X. But I really cant speak to volvo's and how they might act different than merc as you raise them. Most of my detail pics are on my home computer which still has no internet but my prop shafts are just higher than the bottom keel. If I turn a blade perpendicular to the bottom I get a good 2 1/2" of blade tip / transom overlap.
I think 2"up is still pretty conservative and if you run 3blade props which create less sternlift vs 4blades I would probably turn out unless you find someone with your setup to tell you otherwise.
- Marshall
