Prop

[kevinemery]

Had to take the file and some 120 grit to it, quite rough.
Looking a lot better now.
Going to give it a try at the weekend.

[Horsley-Anarak]

Had to take the file and some 120 grit to it, quite rough.
Looking a lot better now.

Watch out you may have got the polishing bug

H-A

[Collector Inspector]

H-A

Pitched up or something......maybe cupped?

www.saving-old-seagulls.co.uk 2013-8-23 16 38 57.png (240.76 KiB) Viewed 547 times

Would seem the way to go aye?



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[kevinemery]

OK wished I never started polishing, should have started with a better prop but it is definitely getting thinner. Had to resort to a sanding disk on a angle grinder to lose the blemishes then back to 120 grit and now 320 grit. I am starting to get shininess.
Will be going shopping tomorrow for polishing kit.
Right this has got me to wondering how all the sanding has affected the balance, the state of the thing when I started was poor so was probably well out of balance anyway.
What do you think of this http://www.youtube.com/watch?v=rPxYBbqFDxE
Should be quite easy to replicate in my shed, are there other low teck methods out there.

[kevinemery]

OK forget what you have seen above, its not that easy to replicate in the shed.

[Charles uk]

Follow Michael's advice earlier in this thread, you could be waisting a lot of effort on a prop not best suited to the needs of your hull & loading, borrow some props that are for 2.5 :1 gearboxes from local Seagull owners & try them out with a revcounter & a gps.

What results (revs/hull speed) did you get with your prop before you started playing?

There are 4 or 5 props that are suitable for your motor, SD swept back, bow tie, your 3 bladed clover leaf & the 4 bladed hydrofan, spring to mind, none of which on your hull will let the motor rev faster than 4000 which means your props doing 1600 revs, a lot different to a heavy stainless performance prop spinning at 4000 revs.

Balancing props is a lot more than just all blades should weigh the same, the pitch on all the blades must be identical as should be the blade area.

[kevinemery]

Had a fantastic day on the Avon, took the family and 2 boats.
OK now getting very confused, both props had the same top speed 4 mph I do not have a rev counter at the moment so I am unsure what rev's the engine was doing.
Now the interesting bit I hope you can help me with.
Cavitation plate has made a big difference, a lot less white water behind the boat.
3 blade prop, acceleration to the end of the throttle, lots of vibration through the boat and white water behind the prop.
4 blade prop, acceleration to half throttle then the engine sounded like it was working slightly harder, no vibration and no white water behind the prop. Maximum speed achieved at half throttle.
She was very smoky today and took a few pulls to start, had to have the throttle three quarters open to get her going.
I have had a quick look at the carb and it looks like someone has taken a file to the insides, not good and may be beyond help.
I understand maximum hull speed and there were 3 adults in the boat, I cant speak for the others but I weigh in over 15 stone.
I presume that the four blade prop is the better option as it reached maximum speed at half throttle, if it was running rich would you expect any more speed with the carb set up correctly. I believe that the hull should be capable of plaining but only have the last owners word on this and I do not have any experience of plaining boats or the power required to get them up there, I never expected a 102 to make the boat plain but did expect more speed from the hull.
There are many reasons why I have ended up with a 9 ft cathedral hull and changing it is not an option.
One way or another I will sort the carb out this week ready for a retest next week.
Any idea's would be most welcome.

[kevinemery]

Sorry about the rambling above, had a few cans yesterday.
Sorted out the carb and found a load of crap between the float chamber and the filter in bolt, so she was probably running lean not rich which would explain the lack of performance.

[Hugz]

Three adults in a 9ft cathedral hull boat is a big ask for any motor! How much freeboard did you have? The motor/boat would have to displace an awful lot of water to move ahead. I'm surprised you managed 3.47 knots. Be interesting to see how it runs one up with more airspace between the hull contours.

[Collector Inspector]

Anzani one on the right and early Olympic on the left.

Back rack, noticed them together poking out of covers.........

Anyone tried fettle on Anzani prop? Probably pitch down slightly depending.

LOTS to work with and they are everywhere. Hub size is equal to clutched gearbox dimension radius as well?

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[Charles uk]

Your Olympic prop looks like it was taken from an SD, we're still waiting for one of you gentlemen to strip one of each right down, to find out how many Seagull parts were used by them & which bits were local manufacture.

We don't even know what the thread patterns were.

[Collector Inspector]

I know Charles, I know.

It will be done....................It is on the shop agenda for summer.

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[kevinemery]

Seagull Racing?
"We are still looking for a good fresh water venue, but they are proving hard to find, are there any near Rugby?" HA
I have found one, I will post in the racing seagulls section the details.

[kevinemery]

Back to this again.
I took the 102 out for a run a few weeks ago and she would not gain speed or rev any higher from half throttle.
She overheated and started to spit steam out so I have striped her down and discovered that the cylinder jacket was full of rust. I have cleaned it out and rebuilt only to discover that she behaves exactly the same in a test tank.
I assumed that the hull was governing the engine speed, I have not got round to getting a rev counter yet but feel sure that the engine has more to give.
Could the prop be affecting the engine speed?
Three blade prop full throttle = 4 mph
Four blade prop half throttle = 4 mph
Confused.

[Collector Inspector]

Pics and details as wotyagot?

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