Seajet
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Have a look at average speed and trying to get anywhere ! As for tripe you might as well cook it on the way, you'll have plenty of time !
fisher 25
- Thread starter gavin400
- Start date
E39mad
Well-Known Member
Have a look at average speed and trying to get anywhere ! As for tripe you might as well cook it on the way, you'll have plenty of time !
I am/was a yacht racer most of my sailing time (Beneteau's, Sigmas etc) but sailed a couple of F25's - particularly the slooped rigged one and have to say I was more than impressed with it's sailing ability so you are again talking tripe sir and again I ask you for your experience with this particular yacht to back up your comments!!!!
Seajet
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Then one would have hoped you knew what you were talking about before spouting rubbish in print here !
I'm happy to say my experience of Fisher and Freeward 25's - excellent though they may be as static liveaboard bases - is limited to going straight past, not difficult with any normal sailing boat.
I've also known liveaboard chums with Fisher 25's, when they ventured out they found their progress rather depressing...
The Fishers were all about conning newbies that they were a ' traditional design ' while in reality demonstrating the worst traits of shallow draft, large wetted area drag, masked prop and heavy weight with tiny sailing ability, including virtually zero to windward !
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E39mad
Well-Known Member
The problem with most (not all F25) is that they have old sails, fixed props, and are generally bought by people who do not know how to get the best out of a sailing boat.
I sailed a new sloop rigged F25 with a folding prop, and was amazed at it's performance as like you I was prejudiced prior to trying one properly. I try not to dismiss any sailing design without having sailed it myself to compare properly.
I sailed a new sloop rigged F25 with a folding prop, and was amazed at it's performance as like you I was prejudiced prior to trying one properly. I try not to dismiss any sailing design without having sailed it myself to compare properly.
Rivers & creeks
Well-Known Member
Agreed, I have all the qualities of the F25 in a bigger package, I must need new glasses because I keep seeing 6 and 7 knot average passage speeds on the GPS log, that can't be right can it?
Greenheart
Well-Known Member
I've been crazy about the F25 for nearly thirty years...never been aboard one, but fell utterly for the sturdy weatherproof appearance...
...although, it would have been part of my plan to buy a ketch, modify the mizzen into a bowsprit, put the mainmast where the mizzen had been, and source an F25 sloop mainmast, stepped forward of the ketch's mainmast...
...such that the very little standard rig becomes something big enough to feel a force two and respond.
I'm amazed and heartened by the PY figures quoted above...I'd regretfully come to suppose that the design is fatally sluggish.
I never much liked the interior - too tight for the four/five people it allegedly sleeps. I had it in mind to make her a properly comfy two-berther.
I'd read of one for sale with a replacement diesel of 39hp! I couldn't decide if that much power would be advantageous (enabling one to hit hull speed at 50% revs...) or whether a diesel is happier running at nearer its maximum, which might have seen the Fisher trying to mount its bow-wave.
I'm equally excited to hear of the Heavenly Twins' low-sounding PY rating. I'm like a kiddie looking at cars' top speeds - I don't always recognise how handicaps translate to real-world performance...but I'd always heard the HT was wretchedly sluggish...so I'm in doubt now.
Apologies for typos. Damned tiny-touch-screen phone!
...although, it would have been part of my plan to buy a ketch, modify the mizzen into a bowsprit, put the mainmast where the mizzen had been, and source an F25 sloop mainmast, stepped forward of the ketch's mainmast...
...such that the very little standard rig becomes something big enough to feel a force two and respond.
I'm amazed and heartened by the PY figures quoted above...I'd regretfully come to suppose that the design is fatally sluggish.
I never much liked the interior - too tight for the four/five people it allegedly sleeps. I had it in mind to make her a properly comfy two-berther.
I'd read of one for sale with a replacement diesel of 39hp! I couldn't decide if that much power would be advantageous (enabling one to hit hull speed at 50% revs...) or whether a diesel is happier running at nearer its maximum, which might have seen the Fisher trying to mount its bow-wave.
I'm equally excited to hear of the Heavenly Twins' low-sounding PY rating. I'm like a kiddie looking at cars' top speeds - I don't always recognise how handicaps translate to real-world performance...but I'd always heard the HT was wretchedly sluggish...so I'm in doubt now.
Apologies for typos. Damned tiny-touch-screen phone!
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Davegriff
Well-Known Member
I've always understood that to drive a displacement hull at hull speed required approx. 5hp per ton + maybe 25% reserve. As a F25 weighs in at about 4.5 tons, that equates to about 28hp, so no wonder owners are dismayed by performance! The underwater shape looks ok to me.
As to over-powering in general though, the worst thing to do to a diesel is run it lightly loaded surely?
As to over-powering in general though, the worst thing to do to a diesel is run it lightly loaded surely?
Greenheart
Well-Known Member
That's what I wondered about. Might the answer be to fit a bigger than standard diesel, with a much bigger prop...so that the speed the engine is happiest working at (say 75%?) still provides more thrust than the standard unit could have cranked out at full revs...
...fast cruising wouldn't require thrashing the engine, with easily enough power in reserve for stormy weather and making way against a fast ebb. Considering Yanmar's 27hp 3YM30 is £6500, why not pay another £2K for the 3JH5E, with 40hp? Only 50kgs heavier.
I've seen Youtube footage of Fishers under power, and the noise was...appalling. Hence I hoped a slower-running unit might help. I've no idea though.
LittleSister
Well-Known Member
It used to be 4hp per ton and no 25%. There's inflation for you!
Our 2.4 ton long-keeler (23 foot) would need 15hp by your formula. We've got 13.3hp and that's more than enough - 10hp (2/3 of your reckoning) would be plenty, and you don't even need that to get to hull speed, except in rougher conditions.
The Fisher 25 is a beamy old girl, and I don't doubt one would want to add a bit to any formula based on displacement alone, but I can't see anyone buying one to go places in a hurry. Settling for half a knot below hull speed could save an awful lot on the price and weight of an engine, as well as making a big difference in fuel consumption.
I see that the Beta website indicates they've previously been re-engined with Beta 25s and Beta 30s (though I don't know how meaningful that is as there are some curious examples from some of the other craft listed).
Seajet
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Dan,
'wretchedly sluggish' does indeed apply to the Heavenly Twins and Fisher / Freeward 25's !
PY numbers are a bit misleading, as they rely on reported performance times so tend to mirror ( pardon the pun ! ) dinghy rather than cruiser speeds.
You're welcome to take my boat any time for a spin alongside ( briefly !
) a Heavenly Twins or Fisher !Incidentally Langstone SC was the birthplace of the Portsmouth Yardstick - PY - the original, like a large ( yard long, funnily enough ) slide rule - is hung on the wall.
Rivers & creeks
Well-Known Member
We had a Heavenly Twins for about 5 years, loved it, great sailing boat. You once knew a chap who had one for a few months - I think I may know more about them than you do!
They made 500 Heavenly Twins, a lot of the last 300 were sold using a demonstrator at SIBS and in the South West which gave test sails. It has a lower PN number than a A22 based on empirical evidence. They are however very badly affected by carrying lots of weight and of course old sails don't help, some also have twin diesels with two fixed props. I know the A22 is faster than time itself and you've regularly overtaken speed boats but that's because you are the worlds best helmsman, the rest of us have to rely on good yacht design and the Fisher and HT are good yachts.
They made 500 Heavenly Twins, a lot of the last 300 were sold using a demonstrator at SIBS and in the South West which gave test sails. It has a lower PN number than a A22 based on empirical evidence. They are however very badly affected by carrying lots of weight and of course old sails don't help, some also have twin diesels with two fixed props. I know the A22 is faster than time itself and you've regularly overtaken speed boats but that's because you are the worlds best helmsman, the rest of us have to rely on good yacht design and the Fisher and HT are good yachts.
Seajet
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Thanks for the confirmation !
In the meantime even mortals are welcome to come along and see what nonsense the HT PY number is, makes a MacWester towing a bucket seem like a Half Tonner !
charles_reed
Well-Known Member
Ah!!
The essential flattery of the paddle-wheel log
Seajet
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Too Right !
11.5 knots; is that in freefall when pushed out of the back of a Hercules ?
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LittleSister
Well-Known Member
Topcat47
Well-Known Member
No Dan, Deisels run best at max torque, usually a little slower than the max power on the curves. The sort of small industrial deisels that form the basis of most sailing boat auxiliaries are also designed to run at fixed rpm. My wee Yanmar drives my relatively heavy 26 footer at 5.5knots very frugally. At 6knots it's using a lot more fuel. At 4 knots, it's does little less than at full torque so needs more fuel to drive the boat the same distance. When running at these speeds, the lub oil is circulating at it's optimal rate and everything else is doing it's job properly like the water pump and alternator.That's what I wondered about. Might the answer be to fit a bigger than standard diesel, with a much bigger prop...so that the speed the engine is happiest working at (say 75%?) still provides more thrust than the standard unit could have cranked out at full revs...
...fast cruising wouldn't require thrashing the engine, with easily enough power in reserve for stormy weather and making way against a fast ebb. Considering Yanmar's 27hp 3YM30 is £6500, why not pay another £2K for the 3JH5E, with 40hp? Only 50kgs heavier.
I've seen Youtube footage of Fishers under power, and the noise was...appalling. Hence I hoped a slower-running unit might help. I've no idea though.
If you over-engine by too much of a margin, the engine will never attain optimal operating temperature under normal conditions. You WILL have cavitation on the prop if you try to drive the hull too hard. This WILL have a detrimental effect on the drive train, which includes the cutless bearing, the coupling, the gearbox and the engine mounts.
I don't know what the ideal engine size for a Fisher 25 is. I'd imagine it'd need more power than my boat (4.5tons on the load cell on the last crane lift-out, about ten years ago). As I'd rather have a Beta 12 these days, although I don't know where I'd put the heat exchanger. Perhaps you might like to go to 10% more power than design requirements but I'd not recommend going above that and certainly not as high as 25%. I guess an Autoprop would be the ideal accompanyment but most of us have to make do with a fixed or folding prop and I can't see what you'd gain from the latter on the Fisher.
Supposed "experts" advised me to fit up the Yanmar 18hp twin when I replaced the old, tired vovlo MD1b. The Yanmar single was an improvement over the old setup. The twin would have been huge overkill. My engine compartment is too small to install a FW cooled engine and I didn't want to have the heat exchanger mounted under a quarterberth so the Beta was ruled out at the time.
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OGITD
Well-Known Member
Steady-on SJ
Thought we reserved this for Newbridge Voyagers.
is that in freefall when pushed out of the back of a Hercules ?
Thought we reserved this for Newbridge Voyagers.
claymore
Well-Known Member
Davegriff
Well-Known Member
There seems to be some confusion in this thread between maximum hull speed and best cruising speed. (You can drive a displacement hull a little over this 'max' of course, but the law of diminishing returns makes it impractical.)
As an example, for a yacht with LWL of 20ft, maximum hull speed would normally be defined as 1.34 * (sqrt 20) or approx 6kts. The generally accepted multiplier for economy/speed balance is nearer 1.25, which would work out to approx 5.6knts.
Fully accept most are already aware of this so apologies to them, but some may not be.
(As a rider, IMHO a boat would therefore be ideally propped to economy at, say, 85% power)
As an example, for a yacht with LWL of 20ft, maximum hull speed would normally be defined as 1.34 * (sqrt 20) or approx 6kts. The generally accepted multiplier for economy/speed balance is nearer 1.25, which would work out to approx 5.6knts.
Fully accept most are already aware of this so apologies to them, but some may not be.
(As a rider, IMHO a boat would therefore be ideally propped to economy at, say, 85% power)
