Anybody know what type of prop should be fitted to a late WSC Silver Century please? Looking at various collection pics across the web I suspect that it may not have been the usual 9 inch diam 5 blade seen on earlier Silver Century units. (I think this may be a Charles & Charles question from reading previous posts on prop types. )
Thanks
Peter
Correct prop type on late Silver Century?
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40TPI
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Thanks for the interest Charles. This is a question on a Silver Century WSC made in the second half of 1978. Not a Plus. From what I can see across the various charts here and elswhere WSC was only used as a prefix in '78 thru '79 so in terms of traditional Silver Century it is "pretty late" , coming just before the change to Model 75.
From that I'm pretty sure that the five blade prop is the right one - either that or there's the option of the weedless version.
I rather like the 5 blade hydrofan, it looks the part with those square blades that remind me of something out of a jet engine, although it's hard to think of two more dissimilar technologies.
It was pointed out to me a while ago that Seagull props generally have a boss diameter and shape that blends with the gearbox, which can act as a rough and ready guide as to their suitability.
The other Charles tells me that a useful power increase may be had by smoothing and blending the propellor blades, with particular attention to the leading and trailing edges. I do know that when the hydrofan was first introduced on the Centuries Seagull claimed a 10 % power increase over the old clover leaf shaped versions.
Mind you if you add up the claims of 'x% extra power' with each successive model or improvement then with a motor made in the seventies you should be able to get a bathtub up on the plane!
I rather like the 5 blade hydrofan, it looks the part with those square blades that remind me of something out of a jet engine, although it's hard to think of two more dissimilar technologies.
It was pointed out to me a while ago that Seagull props generally have a boss diameter and shape that blends with the gearbox, which can act as a rough and ready guide as to their suitability.
The other Charles tells me that a useful power increase may be had by smoothing and blending the propellor blades, with particular attention to the leading and trailing edges. I do know that when the hydrofan was first introduced on the Centuries Seagull claimed a 10 % power increase over the old clover leaf shaped versions.
Mind you if you add up the claims of 'x% extra power' with each successive model or improvement then with a motor made in the seventies you should be able to get a bathtub up on the plane!
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40TPI
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- Joined: Fri Jan 26, 2007 7:08 pm
- Location: North Buckinghamshire, 110 miles south of Yorkshire, England.
...........either that or there's the option of the weedless version.
Would that be the 4 blade anti weed prop? There's a CLW type prop pictured in an auction in another place. The description suggests it is a replacement for Century and Silver Century clutch models. So if CLW is the anti weed prop you mention then was that an option or was it regular fit on the later WSC units?
Leading and trailing edge care sounds an interesting subject in it's own right. Mis-aligned , missing or heavily damaged blades would be expected to reduce efficiency however I wouldn't have thought polishing edges to a fine finish would have made such a difference at this rpm.
Peter
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Charles UK
Try cleaning up your prop by thinning down the blades without changing the pitch & then by cleaning up all the surface finish with a file to produce a prop that is almost shiny with no steps from the casting marks & an airfoil section to the blade with a sharp leading edge.
But first try it out with a revcounter attached & the GPS hanging around your neck then do the prop & try again with the same hull & load.
If you've done a good job & you've got a light hull, you should expect getting on for an extra mile an hour & 200 revs, all that for an hours work & no expense.
When I raced a century plus I found a cleaned up 5 blade hydrofan prop to be faster than it's weed free brother after the same cleaning.
But first try it out with a revcounter attached & the GPS hanging around your neck then do the prop & try again with the same hull & load.
If you've done a good job & you've got a light hull, you should expect getting on for an extra mile an hour & 200 revs, all that for an hours work & no expense.
When I raced a century plus I found a cleaned up 5 blade hydrofan prop to be faster than it's weed free brother after the same cleaning.
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40TPI
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- Joined: Fri Jan 26, 2007 7:08 pm
- Location: North Buckinghamshire, 110 miles south of Yorkshire, England.
Interesting. Thats worth having. For that improvement and the minimal effort involved why didn't Seagull do it on the line, or have their prop casting supplier improve their moulds/fettling?
Think I'd want to do it with a spare prop first! When you say "thinning down the blades" to a sharp edge how far back from the edge are you starting? Do you really mean shaving sharp?
Your suggestion may start a market in all the spare props that currently attract no auction bids in another place!
Think I'd want to do it with a spare prop first! When you say "thinning down the blades" to a sharp edge how far back from the edge are you starting? Do you really mean shaving sharp?
Your suggestion may start a market in all the spare props that currently attract no auction bids in another place!
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Charles UK
Seagull did!
That is until the early 1960s when the bean counters decided that the 3ish workers in the polishing department were not cost effective & that the average Seagull customer was not really concerned with peak efficiency, they just wanted a resonably priced outboard that would start almost all the time.
That is until the early 1960s when the bean counters decided that the 3ish workers in the polishing department were not cost effective & that the average Seagull customer was not really concerned with peak efficiency, they just wanted a resonably priced outboard that would start almost all the time.