Ropecutters

zoidberg

zoidberg

Well-Known Member
Joined
12 Nov 2016
Messages
6,940
Visit site
A brief talk by surveyor Ben Sutcliffe alerted me to the potential problem of a ropecutter mounted too close to the 'deadwood' exit of the propshaft, starving the stern gland of lubricating/cooling water.

Does anyone have any views or experience of this anomaly? Or of a ropecutter affecting the drive from a prop?
 
Last edited:
Anything mounted too close can cause that, an anode is another example. So yes, if mounting a rope cutter, it is necessary to ensure that water flow into the bearings/seals is not restricted - not always easy on some installations...!
 
All decent rope cutters I know of need a fixture screwed into the aft of the P bracket. It may restrict the exit of water a bit. There a lots of them around so I doubt it will do any harm.
As has been mentioned putting a shaft anode too close to the P bracket upside of the flow is not a good idea.
 
The recommendation is at least 15mm space to allow waterflow out of the cutless. Clearly shown on the installation instructions for a Stripper. Often difficult to achieve and fit a decent cutter on a boat (usually long keeled) with the prop in an aperture. putting an anode in the space is also a no-no if it reduces the clearance.
 
Tranona said:
The recommendation is at least 15mm space to allow waterflow out of the cutless.
Click to expand...

May well be worth aiming for, but I think you can get away with less. On my longkeeler I have no rope cutter, but a feathering prop with a substantial hub mounted in an aperture. The distance between cutless/deadwood and hub is just over 10mm. At the forward end of the stern tube is a PSS, which remains cool to touch even after hours of motoring.
 
Yes - if you habitually sail in areas where there are lots of pots or high levels of fishing activity where there is potential for discarded bits of net. P brackets are probably the most vulnerable types of stern gear for catching things and with higher hp engines like yours can experience the worst damage if you do catch something.

Salesman hat off - you can go a lifetime and not pick anything up but when you do you will be glad you fitted the cutter (if it is the proper type). My epiphany was picking up a bit of net in my old long keel boat which jammed the rudder for a while, stopped the engine dead. The next 36 hours of not making it to Cherbourg and turning tail back north, blowing out the main on the way and ending up on Sandown Bay where it was shallow enough to go over the side to clear it resulted in an article in PBO which paid enough to buy a Stripper!. Still have the piece of net in my man cave.
 
Thank you.

It’s a long time since I got something round the prop but I do recall having done so in my little Harrison Butler (Stuart 4, two blade prop in aperture) and in the bigger gaff cutter (three blade on quarter). Probably the quarter mounted prop made me careless, as it wasn’t too difficult to clear it.

So, what should I fit?
 
Kukri said:
Thank you.

It’s a long time since I got something round the prop but I do recall having done so in my little Harrison Butler (Stuart 4, two blade prop in aperture) and in the bigger gaff cutter (three blade on quarter). Probably the quarter mounted prop made me careless, as it wasn’t too difficult to clear it.

So, what should I fit?
Click to expand...
Sorry for delay in replying - have been up in far west Wales with my new boat. all the information you need is here ropestripper.com/strippers.php Expect you will need an AM10 3 blade as I guess your shaft is 1 1/2", but double check the hub diameter of your prop. If you do decide to buy or want more info let me know before you commit.
 
Tranona said:
Sorry for delay in replying - have been up in far west Wales with my new boat. all the information you need is here ropestripper.com/strippers.php Expect you will need an AM10 3 blade as I guess your shaft is 1 1/2", but double check the hub diameter of your prop. If you do decide to buy or want more info let me know before you commit.
Click to expand...

Thank you very much.
 
Kukri said:
Thank you.

It’s a long time since I got something round the prop but I do recall having done so in my little Harrison Butler (Stuart 4, two blade prop in aperture) and in the bigger gaff cutter (three blade on quarter). Probably the quarter mounted prop made me careless, as it wasn’t too difficult to clear it.

So, what should I fit?
Click to expand...
If fitting a Stripper to a P-bracket, ensure that the bolts holding the fixed blade have plenty of thread to screw into. Probably best to include the cutless bearing in the tapped thread. I have ripped two of these out and they are not cheap to replace. I believe Ambassador now sell a collar intended to beef up the attachment but I suspect this would not be needed by increasing the threaded length.
 
Yes there are some skinny P brackets and cutless housings about (early Centaurs for example) but most have enough depth for tapping. suspect that Kukris lovely C&N will have a pretty robust P bracket.
 
My stripper has been in action twice(that I'm aware of) the 1st time was approaching a mooring, engine just idling in gear and engine suddenly stopped - then I noticed a genoa sheet overboard.... no damage and engine started immediately. The 2nd time was motoring across the North Sea to Holland when again, engine suddenly stopped. Looked over the stern and a very large plastic sheet was firmly attached. As soon as engine put in gear engine stopped. We were deciding who would volunteer to go overboard to clear it when I tried going forward and astern and eventually the prop cleared the plastic. Dried out at the nearest opportunity in Holland but no damage fortunately.
 
I have an Ambassador stripper fitted, along with a shaft anode with very limited clearance to the cutlass bearing. It works, probably because there’s a python drive fitted (thrust bearing and CV coupling), which almost eliminates the axial movement of the shaft, and the stern tube is fed by a branch off the raw water-cooling system, to ensure that the shaft seal is always water lubricated, and the flow of water also flushes the cutlass bearing.

So, I guess I’m saying that you don’t always need a lot of clearance to allow the shaft to move as the engine bearings take up the axial load, or to keep the cutlass bearing lubricated. It depends on how the system is designed.

The Ambassador stripper has had many encounters with floating ropes and netting and to date, and has always won. Great bit of kit, But it is noticeable that the are far fewer pot buoys around this year off the NW of Scotland, post Brexit, so it has not had to work so hard.
 
We were extremely pleased that the PO had fitted a stripper. Nine in the morning F8 Old Grimsby Sound. Anchor dragged, well seaweed let go of the it - 100% our fault. Engine on and anchor up but had to high rev reverse at one point. Once sorted and relaxed when we noticed our dinghy drifting towards the beach, the painter cut in two. It had come out of the fairlead.

Losing the engine at that point would have been a little stressful!

Just to note: I am the one who always telling crew to check lines before starting the engine. Pride/falls etc?
 
Tranona said:
Yes there are some skinny P brackets and cutless housings about (early Centaurs for example) but most have enough depth for tapping. suspect that Kukris lovely C&N will have a pretty robust P bracket.
Click to expand...

It does seem quite solid. Shaft, 35mm dia.,
P bracket 40mm thick, propeller boss 60mm diameter. Interestingly, the 43 has a different arrangement with the propeller immediately aft of the keel, and no P bracket.

EDE889C1-6D55-4439-AD92-8CE5FC35AB8B.jpeg
 
Last edited:
You must log in or register to reply here.

Share this page

Top