Cutlass bearing

[doug748]

I have a mind to replace my tufnol stern bearing with a rubber lined cutlass. The new bearing would be about 4-5in long and be housed in a closed stern tube several feet long. Engine 20hp, prop shaft 1in dia.
I do not intend to put a water feed into it.....will I have problems without the feed, anyone any practical experience? Cheers.

 

[VicS]

[ QUOTE ]
do not intend to put a water feed into it.....will I have problems without the feed, anyone any practical experience?

[/ QUOTE ] No personal experience of installing such a bearing but I think you will find that a water feed is essential. It is water that lubricates this type of bearing. It is common just to have a couple of water inlet holes in the housing ahead of the bearing. Take a look around other boats and you will see what I mean.

 

[doug748]

It would be installed in a closed stern tube, so water flow is commonly arranged via the engine cooling water; which I am not very keen on. Surely there is a lot of water down there the problem is normally keeping the stuff out.

 

[nedmin]

No. As you travel thro. the water you pull the water out, its called venturi action.

 

[milfordman]

I do not think you need to be concerned about arranging for a through flow of water for the cutless bearing. The arrangement on my boat is follows:- a 38 HP engine drives a 1.25 inch dia shaft 53 inches long. The bronze shelled 5 inch long cutless bearing sits in the end of the steel propshaft tube. The bearing is cooled and lubricated by the water that enters from the rear end. the forward end of the shaft is sealed via a standard stuffing box, grease supplied via tube and remote screw operated greaser. The old setup usually had a slight drip when running but was stopped after use of the engine by nipping up the greaser screw. I replaced the cutless bearing and the prop shaft this last summer, because of some wear. In fact most of the wear was on the stainless steel propshaft. These parts I am sure were the originals so that would make them 17 years old. The new setup has not had any leak/ drips yet. Therefore the flow through the bearing was always virtually zero, and as I said that lasted 17 years.

 

[milfordman]

Additional info to previous post. The original cutless shell was bronze. As my boat is steel I was advised to replace with a tufnol shelled bearing, so I complied.

 

[doug748]

Excellent, thanks for that milfordsam. Think I will go for it.