Outdrives - major work

[simonfraser]

It's a small hand pump with gauge and a hose that screws into the drain hole . I borrowed it from a friend - sorry no photo.
Not sure where to buy one ..... gearcase pressure tester .

What pressure do you test it at ?

 

[petem]

Thanks for the response so far, some helpful stuff. My recollection was that a re-build should be done around 1000hrs and I was aware of the 'fix' for worn shafts with welding or chroming. Can you advise what sort of money that is Pete?
£6k sounds a bit steep even at VP prices BuceK?

Greg, I don't have the exact cost as it was bundled in with other wok but I think it was a £100-£150 a side so a huge saving over a new shaft.

 

[moresparks]

Regarding pressure testers - I have a Laser 3752 Vacuum Pressure Test kit that seems adequate, together with a hose and connector from a Mercruiser oil pump 18-9781 which screws into the drain hole.

 

[Momac]

What pressure do you test it at ?

Easier if you wouldn't mind please see the manual for the drive for details of the correct procedure - which is available free online

 

[kashurst]

I dunno, I know a fella with a Prestige who got a repair bill for circa £20k for his shaft drive gearboxes. May be less common, but not totally unknown.

how big was the boat 80 feet plus? - sounds like he was well and truly shafted (no pun intended)

 

[Greg2]

Greg, I don't have the exact cost as it was bundled in with other wok but I think it was a £100-£150 a side so a huge saving over a new shaft.

Thanks Pete. That sounds very reasonable and is a vast difference from the £000’s that replacement shafts seems to attract going by reports on here. Any idea how good the repair i.e. how long is it estimated to last for?

 

[petem]

Thanks Pete. That sounds very reasonable and is a vast difference from the £000’s that replacement shafts seems to attract going by reports on here. Any idea how good the repair i.e. how long is it estimated to last for?

I don't like to ask! Some years I guess.

 

[aquatom]

Just pressure testing is pointless. All you are checking is that no oil can leak out. You need to vacuum to make sure no water can enter the drive which is much more likely to happen.

 

[CLB]

Has anyone had both and can do the real maths based on fast cruising mileage?

The main issue is that there are few boats that can have either for a proper compare, and shaft drive boats are usually larger. I have had both and found I got, on average, 1.2mpg on my 37 footer with shafts and get 2.1mpg on average with my 29 footer on drives. This year so far I have covered 800nm so with fuel at £1 per litre I have saved about £1200 in fuel, but have been on a smaller boat. I have owned this stern drive boat for 8 years so potentially I have saved thousands but in reality if I wanted to still own a bigger boat, it would probably be on shafts and I would just accept the larger fuel bill.

how big was the boat 80 feet plus? - sounds like he was well and truly shafted (no pun intended)

It was around 50 foot.

 

[Momac]

Just pressure testing is pointless. All you are checking is that no oil can leak out.

Better than doing nothing.

 

[Momac]

I find it very hard to justify outdrives, I envy the high speed, great handling, fuel efficiency.
for: super efficient - save on diesel, fast boats, sporty handling
against: religious servicing for reliability, expensive oils and parts every two years, fishing line damage, plus the real risk of something serious ruining your summer/bank balance

shaft drive
against: 50% more fuel use when going fast.
for: about as complicated as a horseshoe, sod all gearbox servicing, £60 cutlass bearing every 4 - 8 years, cheap oil every 5 years or so, a £6 anode yearly

if you trash a prop the cost is about the same either way, a new prop shaft for a 50 footer is £900, a recon gearbox is @ £2500 for a 40 footer.
How many threads are there on knackered outdrives? How many threads on stuffed shaft drive gearboxes? (about 3)

I wonder at what annual mileage (note not hours) is it worth having out-drives? Has anyone had both and can do the real maths based on fast cruising mileage?

I would not agree with the fuel economy benefit. We travel in our f33 on outdrive with a f36 on shafts. The f36 does use more fuel but perhaps 20% more. I think that makes shaft drive pretty much equal on fuel use.
I have heard of gearbox issues on shaft drive boats that have been expensive to fix.

 

[Bigplumbs]

I find this thread rather depressing

 

[simonfraser]

not depressing, all kit eventually wears, most of us are aware of this.
interesting to exchange views and be more aware of problems and how to fix them.

without these forums we'd be back to yellow pages !! and knocking or doors

 

[Boat2016]

Better than doing nothing.

Probably not as it won’t give the answer you need, why not do the job properly ? Any good service engineer would own the kit and if they haven’t they wouldn’t get the opportunity to work on my boat.

 

[Boat2016]

I have concluded that nothing on boats is cheap , doesn't matter if it's shaft drive,outdrive or sail. Maybe outboards are the exception to that rule?

I think we need to wait a few more years to see when modern outboards start to require major works, will they be throw away or re buildable ? will all come down to cost once the long warranties have expired.

 

[CLB]

I would not agree with the fuel economy benefit. We travel in our f33 on outdrive with a f36 on shafts. The f36 does use more fuel but perhaps 20% more. I think that makes shaft drive pretty much equal on fuel use.
I have heard of gearbox issues on shaft drive boats that have been expensive to fix.

Are you trimming your F33 correctly? If you read enough boat tests in various mags, you soon get a picture of drives being more efficient than 20%. I guess it also depends on the type of use you are doing. Are those trips typically mostly on the plane, or is there lots of slow speed stuff too.

When I've got more time, i'll be interested to see if i can find any original boat test data for the F36 and the F33. Would be genuinely interested to see the fuel consumption difference at around 20-25 knots.

 

[petem]

I find this thread rather depressing

Dennis, outdrives have lots of advantages (fuel economy, ability to flip in an impact, availability of spares (and props), ease of removal for repair, etc). And in any case, if you want a sports cruiser the chances are that you're stuck with outdrives.

As for the high repair costs, I think some of the above people have been unlucky. As long as you don't scrimp on maintenance the likelihood of a very expensive repair bill is relatively low.

Anyhow, you should be thankful you've only got one!

 

[BruceK]

Pete you forgot the biggie. Outdrives increases interior space dramatically. More (useable) boat for less cost purchase and berthing. People forget to factor that gem in. And the cost saving there is very significant.

 

[Bigplumbs]

Dennis, outdrives have lots of advantages (fuel economy, ability to flip in an impact, availability of spares (and props), ease of removal for repair, etc). And in any case, if you want a sports cruiser the chances are that you're stuck with outdrives.

As for the high repair costs, I think some of the above people have been unlucky. As long as you don't scrimp on maintenance the likelihood of a very expensive repair bill is relatively low.

Anyhow, you should be thankful you've only got one!

I got 2 one on each boat

When I am on the Norfolk broads for example there are hundreds of boats on outdrives that sit on the water and don't come out that often. I cannot believe that all these people are either having the level of servicing done or indeed the massive bills you suggest. I might be incorrect of course who knows

Dennis

 

[julians]

I got 2 one on each boat

When I am on the Norfolk broads for example there are hundreds of boats on outdrives that sit on the water and don't come out that often. I cannot believe that all these people are either having the level of servicing done or indeed the massive bills you suggest. I might be incorrect of course who knows

Dennis

They probably aren't performing that level of maintenance,but then how many of them go out to sea and how many go above 10 knots? I'd suggest ( maybe I'm wrong) a boat on the broads has a much easier life than a boat on the sea (obviously I'm making generalisations).