BATTERY SIZE

Whilst on my trip to the thames meet this year, my starter battery failed. I have a 22 with a anglia engine.
Before I go and buy one , I just thought I would see if I could find out, what other members have fitted.
Reading about batteries, ie the AH rating, it sounds that the Higher the AH is , the more work the Dynamo has to do to replenish the battery. 
At present the old battery is 60 AH. 
I have never changed this battery, and has worked ok for the last 3 years since I have had the boat.
The fact that I have to buy a new battery,would a slightly High AH rating be better.
regards
Alan

Hi Alan, as l see it you have multiple choices.
If the battery is purely for starting replace the battery with similar to what you have or a good quality battery for a small car ( because that's what your engine is for , eg  063, look it up) Don't buy a calcium plate battery, the normal dynamo ( or alternator) technology will not charge it properly and it will quickly fail.
Or you go for a dual purpose battery that will suit both starting and leisure assuming you have room in your bay, I'm sure someone with experience of this type will furnish further advice.

As above. Don't worry about over-working the dynamo. It is pushing out electricity all the time the engine is running so having a higher AH battery just means the control box will be directing the flow through to the battery for a little bit longer.

When I replaced my starter battery several years ago, the guy said 'Blimey, what's that for, a mini?' I replied 'just about.' That battery is now 8 or 9 years old.
Assuming you have a separate leisure battery I'd say just replace it with the same physical size and AH rating.