General Technical/Maintenance questions

[Traveller]

1) A worn rudder stock (rudder vibrates when prop is turning). Not the end of the world I know but any ideas on what the repair cost is likely to be?

2) Also, very slight play on the shaft bearing. Nothing to worry about at this stage but again any ides on costs associated with repairing the bearing?

Finally, when checking out a BMC 1.5 via a river trial, what should I look for. I know that oil pressure and running temp are in the mix. Any other pointers?

 

Thanks

Edited April 12, 2014 by Traveller

[Phil Ambrose]

Hi Colin, can't help with the rudder or shaft bearing but engine temp would be about 80c ± 5 and oil I reckon wants to be about 60 psi idealy.

Phil

[alan_fincher]

This answer has previously been given on the oil pressure topic, and I think most agreed it was correct.....

 

The workshop manual for the BMC 1.5 states that oil pressure (hot) should be 15lb per sq in at idle speed, and 50lb per sq in at normal running speed.

 

The temperature for the engine once the thermostat opens should depend on the thermostat it has fitted. Typical values are either 74 degrees or 82 degrees, and as you won't be able to tell what it has, rising to around either of those numbers is probably about right.

 

If you want to see if it overheats on rivers, you will only achieve that by a fairly long trip out, because the most likely cause of problems could be an undersized skin tank, and these will absorb a lot of heat before reaching the point after consistent hard running, where hot water is being passed back to the engine, (at which point the temperature will start to go higher than thermostat temperature).

If you visually examine the skin tank, and it is presenting at least 8-10 square feet or so to the outside of the boat it will probably have been built adequate for the engine, but if significantly smaller than 8 square feet of external cooling surface, it might well be inadequate in sustained use. (But please don't ask me how we know this!).

[musicman]

Hi.

I had vibration in the rudder when underway and it became necessary to replace the bearing that sat on top of the back deck to cure the problem.

It turned out easy to find a replacement bearing - they were (are) common in the mining industry.

Getting the old one off proved much more difficult than I had thought - I ended up using a grinder to cut through the side of the bearing.

Fitting the new one, however, was a piece of cake. And my problem was sorted. Took a long afternoon to do the job with boat in the water.

Philip

[Traveller]

Philip, it is the bottom rudder-stock bush where the wear is. I would need to be a frogman if I don't dry dock the boat :-)

[OldGoat]

Most all skin tanks are under sized for river use. 8 sq. feet is quite hard to achieve, you need one either side of the swim...

Even fresh water heat exchanger cooling can be inadequate as I discovered on the Thames and had to incorporate my skin tank as well.

 

Now that I've re-engined the boat with a super efficient (thank you Beta) heat exchanger, it runs too cool (Duh!).

 

Some boat builders fit plummer block as the top bearing, these are relatively easy to source, just as well because they don't last forever, because they're not waterproof. FWIW I made and fitted huge rubber washers above and below the bearing.

 

 

 

[alan_fincher]

Most all skin tanks are under sized for river use. 8 sq. feet is quite hard to achieve, you need one either side of the swim...

Even fresh water heat exchanger cooling can be inadequate as I discovered on the Thames and had to incorporate my skin tank as well.

 

Now that I've re-engined the boat with a super efficient (thank you Beta) heat exchanger, it runs too cool (Duh!).

 

Some boat builders fit plummer block as the top bearing, these are relatively easy to source, just as well because they don't last forever, because they're not waterproof. FWIW I made and fitted huge rubber washers above and below the bearing.

 

 

 

 

Most all skin tanks are under sized for river use. 8 sq. feet is quite hard to achieve, you need one either side of the swim...

Even fresh water heat exchanger cooling can be inadequate as I discovered on the Thames and had to incorporate my skin tank as well.

 

Now that I've re-engined the boat with a super efficient (thank you Beta) heat exchanger, it runs too cool (Duh!).

 

 

Assuming swim is a typical 2 feet deep, then the tank can achieve 8 to 10 square feet by being 4 to 5 feet long. Achievable with a single tank if the boat is sensibly designed, but many are not, and a retrofit is often then only possible if a new tank is placed on the outside of the swim, as space not then available to fully sort out an internal tank.

 

On a thermostatically controlled engine you can't actually have too big a skin tank, as controlled opening and closing of the stat should regulate flow through even a massive tank to the point where the engine doesn't over-cool. If your's is over-cooling, it would indicate a missing or malfunctioning thermostat, or that something else is wrong, in my view.

[nb Innisfree]

Actually most modern canal boats have a swim less than 2' deep, more like 21, difficult to achieve sufficient area if the tank is to stop before the bulkhead. We have under 6 sq ft of skin tank, never had probs belting up the Thames with our 40 bhp engine. I think most undersized skin tanks usually cope ok. because engines are rarely run flat out for any length of time usually 75% or so, especially as many are overpropped anyway and max revs reserved for the occasional emergency stop.

[Mike Jordan]

If the top bearing of the rudder is a self aligning bearing in a flange mounting, as many are, you can reduce the rattle of the rudder stock in the bottom mount by the following.

Slack off the two socket headed screws that hold the bearing on the shaft, slack off the four mounting bolts that hold the bearing to the boat and lift the bearing up the shaft about 6mm ( you will normally need to clean off the paint from the rudder stock) retighten the socket headed bolts and then the mounting bolts to press the stock down onto the skeg. This will normally reduce the rattle until you next dock the boat.

Just one suggested addition to the engine assessment, when you have done all the other checks and the test run, use a rag or gloved hand to remove the oil filler cap with the engine running, my experience is that a worn 1.5 will roar like a lion!

Best of luck

Mike.

[alan_fincher]

Actually most modern canal boats have a swim less than 2' deep, more like 21, difficult to achieve sufficient area if the tank is to stop before the bulkhead. We have under 6 sq ft of skin tank, never had probs belting up the Thames with our 40 bhp engine. I think most undersized skin tanks usually cope ok. because engines are rarely run flat out for any length of time usually 75% or so, especially as many are overpropped anyway and max revs reserved for the occasional emergency stop.

Well maybe being "uber picky", but ours, a very standard "Evans & Sons" is 23" deep in the swim, but if you had a properly designed skin tank, say an inch thick, you would also achieve cooling across that 1" of the baseplate as well, so there is effectively "two feet".

 

But even if you take a 21" figure, and ignore the "wrap around" onto the baseplate then 8 square feet still only needs the skin tank to be no more than about 4.6 feet long.

 

As any self respecting swim should be perhaps twice that length, I still claim that it is not hard to achieve the correct cooling area if it is properly incorporated into the original hull build.

 

I know it is nigh on impossible to put one in afterwards, (why ours is now on the outside), but it is ignorance by boat builders that gets it wrong in the first place, rather than the actual impossibility to get it right.

[trackman]

The yard we use told me that when our rudder stock bottom bearing is worn enough he will turn up a cylindrical shim in his workshop to fit onto the end of the stock. That shouldn't be amazingly expensive if done when we have the boat out for blacking.

As regards play in the propshaft stern bearing, this needs to be quite bad to justify bearing renewal. Usually this is evident through problems keeping the stern gland from leaking badly.

The last boat I was involved in, several years ago, where the stern bearing needed renewing, it cost about £750 including a new shaft as well. Plus the cost of getting the boat out of the water and back, of course, unless again it's done when having the blacking done.

[nb Innisfree]

Well maybe being "uber picky", but ours, a very standard "Evans & Sons" is 23" deep in the swim, but if you had a properly designed skin tank, say an inch thick, you would also achieve cooling across that 1" of the baseplate as well, so there is effectively "two feet".

 

But even if you take a 21" figure, and ignore the "wrap around" onto the baseplate then 8 square feet still only needs the skin tank to be no more than about 4.6 feet long.

 

As any self respecting swim should be perhaps twice that length, I still claim that it is not hard to achieve the correct cooling area if it is properly incorporated into the original hull build.

 

I know it is nigh on impossible to put one in afterwards, (why ours is now on the outside), but it is ignorance by boat builders that gets it wrong in the first place, rather than the actual impossibility to get it right.

Actually I've overstated it, we have a bog standard modern 'economy' shell and I asked for an extra 1" on the 18" swim. Standard 7'6" cruiser stern which leaves about 6' swim. Our tank is about 18" x 4'6" max, my observations seems to suggest these sizes are fairly common with other economy shells hence the quite common 17/18" props, different from more traditional stuff though. Ours, like many, is the Skoda of boat shells. To increase our tank size it would have to extend beyond the bulkhead. Could be achieved for the same price with some re-planning, but that would involve change which can be painful for some builders!

[ditchcrawler]

 

 

Some boat builders fit plummer block as the top bearing, these are relatively easy to source, just as well because they don't last forever, because they're not waterproof. FWIW I made and fitted huge rubber washers above and below the bearing.

 

 

 

So did I, laminated two thicknesses of tractor inner tube so it could be fitted with the swan neck in situ. (don't know how to spell situ)

[bizzard]

A large car drive shaft CV boot popped on over the top bearing under the tiller swan neck will give it shelter, just like a nice little umbrella. Big Renault cars or Traffic-Master vans have thick drive shafts. If you can't get the swans neck off use a universal stick together CV boot, these are designed to be altered with a sharp knife to fit different sizes, indeed these boot kits should come with a modeling knife, Locktite rubber glue and securing clips. Secure it around the stock with a hose clip. All available at car spares shops and motor factors.

[ditchcrawler]

A large car drive shaft CV boot popped on over the top bearing under the tiller swan neck will give it shelter, just like a nice little umbrella. Big Renault cars or Traffic-Master vans have thick drive shafts. If you can't get the swans neck off use a universal stick together CV boot, these are designed to be altered with a sharp knife to fit different sizes, indeed these boot kits should come with a modeling knife, Locktite rubber glue and securing clips. Secure it around the stock with a hose clip. All available at car spares shops and motor factors.

Never thought of that when I made mine. Still mine was FREE so it must be good.

[Traveller]

Thanks for the info all. Now back from the final river trial. Spoke to surveyor re shaft bearing and he said the movement is minor and no action is necessary. The rudder-stock bearing is worn but the vibration is only evident if I lean on the rudder. Yes, it does need sorting but it is nowhere near the end of the world.

 

Engine ran like a dream with no major smoking (in fact none after a couple of mins) and the oil and temperature remained within the tolerances discussed on this thread. The only problem I did have was with the cold start. The instructions on board say turn key to left (red marker) and hold for thirty seconds and then turn further left (to green marker) to start. After starting the key should be turned all the way to the right (blue marker). For a hot start the key should be turned to the right. Turned the key left to the red marker and the key clicked into place (I did not have to hold it there) but no lights came on. Left it for 30 seconds and then turned further to left and ignition light came on and engine turned over. It took several attempts before the engine started and I wonder therefore if the preheaters are working (or am I doing something wrong)? Hot starting did not present a problem.

That was it. Boat handled well and the hull survey is very good. There is also a boat safety until 2018. She badly needs blacking but the vendor has agreed to deduct this from our agreed price, he has also agreed to pay this years license. So, it looks as though we now have a nice old (1978) Peter Nicholls hull. The inside is original and in great condition. The outside is ok but tired paintwork wise. Only other problem is a leaky side hatch but we can sort that.

Incidentally, I could not ask the vendor about the cold start as he knows nothing about boats. He inherited this from his dad who has sadly passed.


Colin

Edited April 13, 2014 by Traveller

[Traveller]

Just wondered if anybody has got any pointers re the preheating referred to in my last post

Thanks :-)

Colin

[Phil Ambrose]

Heaters can norty taking longer to heat up with age, try leaving them on heat for 45 seconds. You can get them tested and replacements should not be too hard to obtain

[Traveller]

Thanks Phil, it is just a case of turning the key to the appropriate position then? On my old Broads cruiser I had to hold the key against the spring.

Looks like we may well be coming to Riverside Island next month so is there a "nice man" who can give the engine a service for me?

Thanks

Colin

[Phil Ambrose]

Look forward to seeing you, will pm you the name and number of the chap, he as done work for me and looks after many other boats here, diesel mechanic by trade now a boat fixer upper, sells them too and reasonably priced.

Phil

[Exy]

Hi there,

Someone who have another opinion about Evans & Sons?

I found one of 2001 in interesting price but with a extensive water damage due to a following flooding ( floor and the bulkheads require replacement).