Running in reverse on swing mooring - battery charging

catlotion

catlotion

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An old topic I know, but I've been scouring the forum for info on this and no real definitive answer...

We're moving to a swing mooring and I think we may sometimes experience a battery charging issue. We have two 110ah batteries and hope to run a fridge and Webasto heater (prob not both at once). Before investing in wind/solar/charge regulator/generator/monster alternators, we're going to see how we get on.

We motor about a fair bit (wind can be surprisingly elusive at times on Windermere) so I think we'll be ok generally, but I was wondering about engine charging if we do need to charge batteries on the mooring. I'm familiar with the glazed bore debate and on the basis of opinions here, I couldn't decide either way (and don't want to start that argument again!).

It seems obvious that running the engine faster under load will increase charge rate and reduce any potential bore damage, but how practical is this on a swing? I've read people running in reverse to increase the load but how much rpm is sensible? Will it stress the mooring tackle excessively? We have a Beneteau 350 and the mooring has a double block...

cheers!
 
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My vote goes to solar panels. Silent, work all day. I've done the alternator route at anchor, it takes hours even with a multi-stage charger. If you want to get the max out of the alternator, the engine needs to be faster than tick-over, in my case, about 1300 rpm.
 
I believe that bore glazing is a consequence of condensed exhaust gases on cold bores. This is very well known in reciprocating gas compressors and seems a likely mechanism in engines. To minimise the problem as far as possible you need to warm the engine up as quickly as is practicable. Although I rarely need to charge by engine at anchor, when I do I use about 1500 rpm until the coolant is warm, then reduce to about 1000 rpm. Your mooring will take this sort of load without any problem, and if not you will know that your boat has been saved from blowing away in a storm.
 
Agreed, if you can't safely run half revs on the mooring, then your tackle is not up to the task! I've done this after one of my better cock-ups - used "modern" engine oil in the gearbox and the clutch slipped immediately. Had to use flushing oil to clean it up, so we tugged at the mooring for about an hour to churn up the gunk. Best performance afterwards and gearbox oil cleaner than I'd seen in a decade!

Vyv can tell you all about why the modern oil didn't work. Had to go to an agricultural supplier for straight low grade 30SAE.

Rob.
 
"It seems obvious that running under load will increase charge rate"
Surely, it's the RPM of the alternator which determines the output?
 
charging

Hi we are on a swing mooring on windermere and never a problem charging, your tackle will take it no problem but we fitted a solar charger and its perfect cheers
 
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