Emergency Fan Belt

[Dockhead]

My boat has two alternators -- one regular Hitachi 80 amps * 12v and one large school bus alternator 100 amps * 24v.

The big one is connected to the 24v house bank and generates bulk power. It's a key element in my power system and I will be carrying a spare.

The small one does nothing but top off the starting battery -- there are no loads on this system whatsoever.

The electrical failure of this alternator would not be any kind of a problem -- I can easily charge the starting battery with the inverter, and I can easily jump the engine from the generator start battery.

HOWEVER, if the bearings failed, I would be in a world of hurt, because the same belt drives the engine's fresh water pump.

I don't want to carry a whole spare alternator just for this case.

I WILL carry a spare bearing set, but I'm not sure how difficult it will be to replace them at sea.

How about one of those "emergency fan belts", which are adjustable, and which presumably can be adjusted to bypass the alternator and drive the fresh water pump directly?

Anyone have any experience?

[Pete7]

Why not have a local electrician give it the once over, a clean out and fit new bearings. Then with a new belt you won't have to worry during the trip, or change an alternator in a lumpy F6.

Pete

[Dockhead]

Originally Posted by Pete7

Why not have a local electrician give it the once over, a clean out and fit new bearings. Then with a new belt you won't have to worry during the trip, or change an alternator in a lumpy F6.

Pete

That's a good suggestion; thank you.

[RaymondR]

For many years I carried a 12V impeller pump for which I had a number of adapters to allow use if the water pump">raw water pump on my engine failed. Only had to use it on the engine once but found it very handy to have for fuel transfer and polishing, water pumping etc. If you go this route make sure the pump has a nitrile impeller.

[Wotname]

Originally Posted by Dockhead

..........

HOWEVER, if the bearings failed, I would be in a world of hurt, because the same belt drives the engine's fresh water pump.

I don't want to carry a whole spare alternator just for this case.

I WILL carry a spare bearing set, but I'm not sure how difficult it will be to replace them at sea.

How about one of those "emergency fan belts", which are adjustable, and which presumably can be adjusted to bypass the alternator and drive the fresh water pump directly?

Anyone have any experience?

You could take the 12V alternator home, change out the bearings and you will soon know if you can do it at sea. Of course, you won't need to as you will have the new bearings already fitted .

As for the emergency fan belt, I have not used one but considering the load will be light in your application, I would suggest / guess it would be fine. Again this could be trialled before it is needed in anger.

[deblen]

Not sure about UK prices,but in N.A. you can buy a rebuilt marine alternator-50-60-80-100amp for $100 or less.
Much easier to just keep one each for spare & swap the whole alternator out while at sea.
Just make sure that the pulley on the rebuilt spare is identical to the OD & groove width existing on boat units.
Also,verify that the mount & slot adj. bolts are same as original.
Buy a 1/2" drive electric impact wrench (as used by tire shops) plus a socket to fit the alternator shaft pulley nut.It's the only way to remove/install an alternator pulley,among other things.

Len



Typical

https://www.youtube.com/watch?v=RhFoFSe1A3U

[james247]

Originally Posted by Dockhead

My boat has two alternators -- one regular Hitachi 80 amps * 12v and one large school bus alternator 100 amps * 24v.

The big one is connected to the 24v house bank and generates bulk power. It's a key element in my power system and I will be carrying a spare.

The small one does nothing but top off the starting battery -- there are no loads on this system whatsoever.

The electrical failure of this alternator would not be any kind of a problem -- I can easily charge the starting battery with the inverter, and I can easily jump the engine from the generator start battery.

HOWEVER, if the bearings failed, I would be in a world of hurt, because the same belt drives the engine's fresh water pump.

I don't want to carry a whole spare alternator just for this case.

I WILL carry a spare bearing set, but I'm not sure how difficult it will be to replace them at sea.

How about one of those "emergency fan belts", which are adjustable, and which presumably can be adjusted to bypass the alternator and drive the fresh water pump directly?

Anyone have any experience?

The main tool is a bearing puller. Why not a spare generator. Wrapped in waxed paper easy to hide away.

[mickt243]

Another option- find what size fan belt you need to run just the water pump, without running the alternator, and have some that size in your kit, practice using locally before heading out to the great beyond

[Wotname]

Originally Posted by mickt243

Another option- find what size fan belt you need to run just the water pump, without running the alternator, and have some that size in your kit, practice using locally before heading out to the great beyond

This assumes you can tension the belt without the alternator fitted.

[El Pinguino]

Speaking as one who has done and is still doing a bit of remote area cruising much of it in areas where a working engine is essential I carry a spare FW circ pump, a spare alternator (both belt driven ) and a spare starter motor ( Volvo MD17D.... left handed ).

And yes I have had to make use of all three over the years.....

Re the spare belt... take out the FW pump...any belt would foul the starter ... take out the alt... no way of tensioning the belt.

Sometimes the simplest solution is the best solution.

[jimbunyard]

Originally Posted by Dockhead

How about one of those "emergency fan belts", which are adjustable, and which presumably can be adjusted to bypass the alternator and drive the fresh water pump directly?

Anyone have any experience?

Many years ago I got one at a trade show and played with it, installing it on a non-idler belt drive fan. As I remember, it only had a a single 'locking tab' connection system, it was quite a bear to change the length, and it was rather loose to boot. (but the load on the w/p as compared to an alternator is much lighter, so it mightn't matter)

According to this video

https://www.youtube.com/watch?v=LFu_ojAw-K8

'They've' changed the design, and the process now's a snap...at least in the video...

Since they're relatively inexpensive, seems worth a try to get one and see if it's useful in your application, if it works, keep one prepared at the proper length.

Of course, if it works you could likely just get the right length normal belt, and use the 'roll it on' technique shown in the video to install it...if it's very tight to install, you might consider some type of engine room mounted starter switch, if you don't already have one installed...

[Steven UK]

I would expect the load on the water pump to be much less than the alternator when under load. So I would have some confidence in the temporary belt design shown above. There is another style I have seen in use on farms which is a stretchy (somewhat) belt that you cut to length then join with a male-male barbed fitting. There cheap give them a try and let us know.

[Dockhead]

Originally Posted by jimbunyard

Many years ago I got one at a trade show and played with it, installing it on a non-idler belt drive fan. As I remember, it only had a a single 'locking tab' connection system, it was quite a bear to change the length, and it was rather loose to boot. (but the load on the w/p as compared to an alternator is much lighter, so it mightn't matter)

According to this video

'They've' changed the design, and the process now's a snap...at least in the video...

Since they're relatively inexpensive, seems worth a try to get one and see if it's useful in your application, if it works, keep one prepared at the proper length.

Of course, if it works you could likely just get the right length normal belt, and use the 'roll it on' technique shown in the video to install it...if it's very tight to install, you might consider some type of engine room mounted starter switch, if you don't already have one installed...

Thanks, hot tip!!

[Dockhead]

Originally Posted by Steven UK

I would expect the load on the water pump to be much less than the alternator when under load. So I would have some confidence in the temporary belt design shown above. There is another style I have seen in use on farms which is a stretchy (somewhat) belt that you cut to length then join with a male-male barbed fitting. There cheap give them a try and let us know.

Thanks; I believe that this is logical.

If you buy the alternator from Yanmar, it's $1000. An aftermarket one, though, is only $100 or so.

But I don't really want to carry a spare -- I have half a ton of spares and tools as it is and I'm fighting with volume and weight. I think the risk of failure is extremely small since there are no loads on it, and as you say, the water pump without any alternator is a very small load.

I am encouraged now and I think I will acquire a couple of different of these devices.

Yet another plus is that getting the main engine back into service after an alternator failure will be much faster if all I'm doing is removing or cutting away the belt and installing one of these.

If I carry a spare set of bearings, then I only need to get to the nearest auto electric shop, or maybe I can even change them out myself -- I do have a bearing puller on board. Bad bearings is the only risk since I don't really care that much about the electrical output, and anyway with no load on the electrical parts of the alternator it is almost impossible to imagine how it could fail. I guess I might as well have brushes, if I'm ordering bearings.

[mako]

Dockhead, you don’t have two belt grooves so you can separate the two?