4-blade weedless prop for 40 plus

[atoyot]

More along the classification of trivial changes or experiments: Ebay (US) has an 8", 4-blade weedless prop up for bid. I can't get to Ebay from a computer at the moment of this post, but can see it on my cell phone internet service.

Thus, I can't offer the auction number but the seller is "fish-on71" and the listing is titled, "British Seagull 4 blade 8" alum weedless propeller prop" and ends 1st Oct '09 @ 23:33z. Has anyone here any comparisons to make between a standard 4-bladed hydrofan vs. a 4-bladed weedless prop of the same size and for the same application? (Mine is at present a hydrofan.)

I'm happy enough with the engine the way it is, of course. I do like the look of the more modern, 4-bladed prop but it's not worth spending money on it if there's no practical difference. For instance, if it has a higher effective pitch for my plaining sailboat hull, then that could be of interest. Comments welcomed.




Cheers,

Ted

[Charles uk]

The 40+ weedless prop only has 3 blades.
The model 75 weedless prop has 4 blades.

Both were designed for a 2.5 : 1 clutched gearbox.

A 40+ has a 3.5 : 1 non clutched gearbox.

I'm not sure that your 40+ will drive this prop, but it will be an interesting experiment to see if with the lower ratio box, it will drive the 4 blader with the higher pitch.

[PeterW]

Item is 370264890131

Cheers

Pete

[atoyot]

The 40+ weedless prop only has 3 blades.... it will be an interesting experiment to see if with the lower ratio box, it will drive the 4 blader with the higher pitch.

That mounted on a higher reduction gearbox would be interesting to see and it looks as if you're saying that the 4-blade weedless had a higher pitch than the 40+ hydrofan. I guess the other question is, whether the overall prop hub is the same diameter of that of the hydrofan so that it'll fit against the gearbox properly

I'll keep an eye on it and see what happens.

Here's the auction and description -

http://cgi.ebay.com/ebaymotors/ws/eBayI ... &viewitem=

[Charles uk]

Model 55, dia 8", pitch 7", total blade area 28.26 sq", gear ratio 2.5 : 1.
Model 75, dia 8.25", pitch 7", total blade area 39.00 sq", gear ratio 2.5 : 1.

I have no figures on the hydrofan

I've only looked at props that could have a racing application

[woodbutchergraham]

Done that , polished up a four blade weed free, stuck it on my old 40+. It pushed up the revs, used more fuel didnt improve the performance noticibly. But in its defence didnt pick up much weed, i think next time out may take both and my sat nav as a speed comparison.

[Hugz]

Satnav and a Seagull. The mind boggles

[Charles uk]

Seagull, GPS & revcounter, you need to know if it's flogging itself to death!

[atoyot]

Seagull, GPS & revcounter, you need to know if it's flogging itself to death!

But seriously, I've read elsewhere that there's benefit in balancing the prop. Sounds like possible overkill, but then, it's massive by any prop standard and is spinning at 3500+ revs.....

[Collector Inspector]

Maybe the "Prop" is spinning more like 1200 rpm if the motor is singing at 4200rpm, or there abouts?

3.5:1 reduction?

Then would that be about the limit for any fan type prop not under load regulating engine rpm to less than 4200rpm anyway?

Just a thought.

B

[atoyot]

Maybe the "Prop" is spinning more like 1200 rpm.... 3.5:1 reduction..?

Uh, yeah. That's something I forgot. The claim was that off-balance props could cause as much vibration as the engine head. At 1200 rpm? Doubt it. Well, being me, I'm going to have to shove a 1/2" dowel or bolt into my cordless drill and spin a (hydrofan) prop at full rev's and see if I can detect anything while holding a Bullshit-Evident Vibration-Effected Rotational Augmentation Generating Engagement in the other hand. My guess is that it's a non-issue, but rather just something I read up on another board under the topic of Seagull racing. What, there's someone even more anal than me?

Anyway, back to replacing parts in a Bing carberuettor due to poor storage techniques....

[Collector Inspector]

Probably, Yeh........


B

[Dino - UK]

Prop will probably stay still and the boat will spin.

[Collector Inspector]

Love that!

LOL

B