There is a lot of different options being suggested on here, some are fair enough on a yacht, others are not (any kind of air starter will really be a non starter if you pardon the pun) unless you are sailing something over 100 feet long!
My opinion is if you want to have a backup starter just in case, the mechanical “wind up spring starter is your best option, it is self contained and gives you one start per wind
up. Winding it requires quite a bit of space surrounding the starter and also require quite a bit of effort and you MUST wind
it all the way to the “red” in the inspection
window, its a big mistake to under wind it. If your engine
is a good starter, then these are perfect for emergency
use. If your engine
requires a lot of turning over before it starts, then these are not the best option. Again, only my opinion, these are wholly unsuitable as your main and only starter.
Your original question was about Hydraulic starters, you could use these as you only starter but it requires additional equipment
IE Hydraulic accumulator, a hydraulic oil
tank, usually a foot starter valve, and pump
to recharge the accumulator after the start.
You would then have a choice, if its going to be your only starter, you really need and engine driven charge pump
and an emergency
backup hand pump, but if the starter is only for backup, then you only require a hand pump (and accumulator & tank)
Just for your info, a hydraulic accumulator has inside it a bladder which is prefilled to a precise pressure with Nitrogen, this only requires checking maybe monthly and refilling very occasionally possible 4 yearly (the accumulator is normally a certified piece of equipment
because the pressure inside is usually around 3000psi)
To pump it up by hand usually entails pumping the one meter (at least) long handle for some considerable time, maybe 10 to 15 minutes (depending on the size of your accumulator) and some considerable effort, not to be taken lightly. Just for info, when you pump the accumulator from zero pressure on the gauge the pressure rises quite quickly until it reaches the bladder pressure (maybe around 1000psi (thats just a guess) thereafter each stroke of the lever only increases the pressure on the gauge a tiny amount because you are now compressing the bladder, (before, you were only filling a very small space surrounding the bladder)
Someone stated above that you would only get one start, that is not entirely correct as it again depends on the size of your accumulator.
Personally, although its great to have these types of “out of the box” discussions the reality is, electric
is the way forward, As a retired maintenance engineer
, my advise is down to purely good regular planned maintenance
of everything, Starting with batteries
, drive belt, starter, all cable connections and at the first hint of any issues, investigate and repair ASAP, using good quality parts
(preferably on board) and services (if you are not doing it yourself)
PS, as a possible source of an entire second hand system hydraulic system, you could try and find a supplier/maintainer of offshore
or ships life boats which often have these systems fitted as standard and life boats are quite often replace within the life of an oil
platform, just a thought.
You don't say where you are sailing Europe
or USA? I know a company in Scotland
which could probably supply you an entire system!
All the best