Prop Shaft

[sangerdan]

This is way outside my expertise. but I've seen a hole in the strut supposedly to let water into the barrel. When you are sitting still the barrel should fill except for trapped air; even if nothing was forced in by forward motion is there enough of a low pressure area at the prop end of the barrel to suck the water out? If so probably not enough to suck a vacuum so it would have to pull water in from somewhere. How much water is needed to do the job? I'll bet all the motions going on in that area are violent enough to make sure fire knowledge if water is flowing through the strut bushing the way we'd like to think impossible.

[gn7]

I've seen some little sleeves that had a taper to the front that had holes drilled so water could supposedly pass through to the bushing. They only used two little set screws to hold them in place though. Can you get your shaft out without removing the rudder?

Yeah,I think Bergeron may have made those up. I got one that was on a used shaft I bought for the material. It would work better than nothing. But back to back speed runs didn't show ours made any difference and the bushings last so we I leave it. As touchy as the boat is to props and its location on the shaft, I would have thought it might jack with the handling of the boat as well. But Bill says it doesn't. Move the prop back a 1/8th, and sounds off like a little girl.

[gn7]

This is way outside my expertise. but I've seen a hole in the strut supposedly to let water into the barrel. When you are sitting still the barrel should fill except for trapped air; even if nothing was forced in by forward motion is there enough of a low pressure area at the prop end of the barrel to suck the water out? If so probably not enough to suck a vacuum so it would have to pull water in from somewhere. How much water is needed to do the job? I'll bet all the motions going on in that area are violent enough to make sure fire knowledge if water is flowing through the strut bushing the way we'd like to think impossible.

I personally believe, after putting the collar on it have little effect on bushing life, that it is NOT the pressure in front the feeds the bushing, but the negative behind the strut sucking water in. I don't see the benefit of the little hole in the set screw type collar Hotwater mentioned. I really don't see the need for a hole in the strut.
It takes very little water in the strut bushing to keep it happy. Some people swear it creates a hydraulic wedge like a main bearing. That's pure BS, because the length wise grooves in the strut won't allow a wedge to form.

I have had to run the boat in gear on the trailer before, and just let a garden hose stream on the shaft at the strut, and it was fine. Ran it for 10 15 minutes, no problem. Do it with out the hose, and you lose the bushing in a minute or less. If I had to bet on a magnaflow impellor or a strut bushing without water, I'd bet on the magnaflow out lasting the bushing.

[HotWater]

This is way outside my expertise. but I've seen a hole in the strut supposedly to let water into the barrel. When you are sitting still the barrel should fill except for trapped air; even if nothing was forced in by forward motion is there enough of a low pressure area at the prop end of the barrel to suck the water out? If so probably not enough to suck a vacuum so it would have to pull water in from somewhere. How much water is needed to do the job? I'll bet all the motions going on in that area are violent enough to make sure fire knowledge if water is flowing through the strut bushing the way we'd like to think impossible.

I've seen a strut like that on a 68 Aquacraft. I thought it was a neat idea but I would assume the part would'nt be as strong.

[HotWater]

Djunkie brings up a question of extra drag from a collar. I have often wondered if there is aeriation from the strut or if a collar is used would it be worse? GN7 stated no difference in speed testing so maybe it does'nt matter.

[gn7]

I've seen a strut like that on a 68 Aquacraft. I thought it was a neat idea but I would assume the part would'nt be as strong.

OH THAT HOLE. That hole has nothing to do with the strut bushing. Its actually a pickup for the engine water. Cool idea, saved drilling another hole in the boat before they started putting the pickup in the cav plate. It worked reasonably well for the power the made in the day. Nicson made a slightly different version than the one pictured, where the inlet was on the side of the barrel right where the blade met the barrel. It didn't feed water to the bushing either, but from the outside it may have looked like it did.
There was a cracker running that had the water pickup for the engine in the rudder blade. Series of holes drilled in the side of the blade on a forward facing angle, that connected to a hole drilled vertically down the rudder shaft. Cool setup, but I think they ditched it

[steveo143]

Dan Bell, the owner of the GN boat "Priceless", makes the tapered shaft safety collars with water passages in them. They are made in both left and right hand prop directions.

[gn7]

Dan Bell, the owner of the GN boat "Priceless", makes the tapered shaft safety collars with water passages in them. They are made in both left and right hand prop directions.

Now that think about it, that is who made the one I have. Never use it. I do have kind of a issue with putting dimples or flats in the middle of the shaft, so its never been on the boat.

[HotWater]

OH THAT HOLE. That hole has nothing to do with the strut bushing. Its actually a pickup for the engine water. Cool idea, saved drilling another hole in the boat before they started putting the pickup in the cav plate. It worked reasonably well for the power the made in the day. Nicson made a slightly different version than the one pictured, where the inlet was on the side of the barrel right where the blade met the barrel. It didn't feed water to the bushing either, but from the outside it may have looked like it did.
There was a cracker running that had the water pickup for the engine in the rudder blade. Series of holes drilled in the side of the blade on a forward facing angle, that connected to a hole drilled vertically down the rudder shaft. Cool setup, but I think they ditched it

Yep you right! Guess I really did'nt pay attention to it. This must have been a race boat since it's got a drop through strut.

[gn7]

Now that's a unique piece. I can't say I have ever seen one like that.