Encased Prop Shafts?

[Lured Away]

Is this a new design? I have seen a few pics recently of larger sportfisherman that appear to have their prop shafts encased in a tube. Just looking for some more info on the design, what manufacturers are using it and what other benefits/results are there besides no growth on the shaft itself?

[Phat Mann]

Shaft Tubes are becoming quite popular. We put them on after first year without them. We wanted to see how they performed on another Paul Mann boat.

We added about a knot of speed but better yet about 5 GPH in fuel consumption.

Results were even better for the other PM boat. While results vary, it seems most are please with increase performance.

[hubris 1]

how does the cutlass bearing stay wet?

[fishfighter]

They had a boat on here that was having one installed with pictures,but I can't fine it.Cooling the cutless bearing was one of the things I wanted to know too!

[rugman]

stopler boats have used them for quite a while they are sealed and filled with oil

[pitch bait]

There are two holes in the middle of the shaft tube that let water get to the bearing in the strut. The orward bearings in the shaft tube are lubercated throught the dripless cutlass. It requires an evtra set of bearings. You press your normal bearing in from the prop side of the strut then take another ful bearing and cut itin half and press it in behind the full bearing. It puses the fullone out the back side like 4"
Then you do the same on the shaft tube but you put the full bearing in last. The tube is a then glassed in alittle and there are a couple small set screws. They are great whn they are tight It is importand to check them cause it dosent take much to get them lose.

how does the cutlass bearing stay wet?

[stimmy]

Shaft Tubes are becoming quite popular. We put them on after first year without them. We wanted to see how they performed on another Paul Mann boat.

We added about a knot of speed but better yet about 5 GPH in fuel consumption.

Results were even better for the other PM boat. While results vary, it seems most are please with increase performance.

Those are big savings. Where do you think the increased efficiency is coming from? Lower friction due to the shaft not rotating in the water? Better bearings reducing shaft flex/prop wobble?

[clt_capt]

Those are big savings. Where do you think the increased efficiency is coming from? Lower friction due to the shaft not rotating in the water? Better bearings reducing shaft flex/prop wobble?

I'd say those are major contributors, along with no growth on the shaft to impede it

[Phat Mann]

Yes I think those are good reasons for the increased performance.

I have yet to hear a negative.

[Fortunate One]

Do you guys know where I can get some pictures and or some information on how to install these correctly? If not perhaps a phone number of a yard or a builder that's willing to share some information on exactly how large the water inlet holes need to be on the tube, and or diagrams on how it's done. I do recall seeing something about this in this forum a little while back.

We're getting to the point where we're going to be thinking about ordering shafts and strutts and if the gains are like whats been listed above then I'd like to incorporate this into my new express.