Prop size

[rog guiver]

Four blader from Reading Marine. Nice bunch, very helpful.

 

Two seasons with the four blader and much, much better than the previous (three blader) on not picking up weed.

Edited August 2, 2007 by rog guiver

[Amicus]

Four blader from Reading Marine. Nice bunch, very helpful.

 

Two seasons with the four blader and much, much better than the previous (three blader) on not picking up weed.

 

 

This is sommick I've bin wondering about, years ago when I faffed about on salty boats there was a fing called a "weedless prop". A quick googly throws up some pictures;

 

http://www.miwheel.com/MIWheel/products/in...al_catalog.html

 

Wonder why these are not used on inland waters?

Edited August 3, 2007 by Amicus

[John Orentas]

This is sommick I've bin wondering about, years ago when I faffed about on salty boats there was a fing called a "weedless prop". A quick googly throws up some pictures;

Wonder why these are not used on inland waters?

 

 

This is one of those topics were we must be careful not to start reinventing the wheel, all those odd ideas have been tried before and as with any type of design or innovation you can be fairly sure that if it's not in common use today it is because it didn't work in the first place.

 

The various designs of tube propellers will sooner or later get fouled up and you will probably need to find a dry-dock to clear the blockage (and you may well find yourself cutting the lot off in frustration). Those supper efficient 'unsymmetrical' jobs you occasionally see on fast sea boats may squirt you through the water but only in one direction, the first time you need to go back-wards you will find you can't.

 

Those nice 'hooky' profiled things may be designed to grab the water but they also have the perfect shape to hook up every plastic bag and bit of rope for miles.

[Proper Job]

Four blader from Reading Marine. Nice bunch, very helpful.

 

Two seasons with the four blader and much, much better than the previous (three blader) on not picking up weed.

 

Rog

 

Sound interesting - is that Reading Maine Co or Reading Marine Services? Reading is not a million miles away from me.

 

Bruntons recon a 4 blader is better at reducing cavitation when going from ahead to astern. How does this comapare with yours?

 

What made you change from 3 to 4 in the first place?

[rog guiver]

Rog

 

Sound interesting - is that Reading Maine Co or Reading Marine Services? Reading is not a million miles away from me.

 

Bruntons recon a 4 blader is better at reducing cavitation when going from ahead to astern. How does this comapare with yours?

 

What made you change from 3 to 4 in the first place?

 

 

I was fitting out a Reeves hull that Reading Marine also use. They had moved from the "normal" three bladed prop to a four to reduce the diameter and (hopefully) reduce the prop noise through the hull. Thought it seemed a good idea and am very glad I did.

 

Reading Marine are based in Aldermaston.

 

PS this is what this Forum is all about, helping others, discussing our passion (canals) and the things that float in them. I almost left when one of my posts resulted in a post commenting about my sex life. It was only after calming down and ignoring the plonker, not rising to the bait, that I decided to stay.

Edited August 3, 2007 by rog guiver

[John Orentas]

All this is seems very strange to me, never in my life have I seen a four blade prop on a narrowboat.

 

Must have missed the bit about the plonker have you a link ?

[Timleech]

All this is seems very strange to me, never in my life have I seen a four blade prop on a narrowboat.

 

I have, that particular one worked pretty well but it was too lightly built for canal use & soon got bent & battered. I may even still have it somewhere.

The theoretical disadvantage of having an even number of blades is that two are masked by the stern post at the same time, so there is more likelihood of vibrations from that source. I don't suppose it's anything you would notice at normal canal speeds, but maybe if stonking along a river at speed, and particularly if your boat has a wide sternpost.

 

I wonder if there is a fundamental difference in effectiveness between a 3-bladed prop witha large blade area, and a 4-bladed one with normal bats?

 

Tim

[Proper Job]

28 x 21 prop

are your heasure ments for a sea going boat or narrow boat think you may struggle to get 28 " in .

my kelvin according to manufacturers manual says 17 " but i run it with a 22 x 17 after speaking with crowthers who reckomended a 21 x 17 which is doing just fine and that gives me about a 1 1/2" clearance

 

ps i found some info on your engine the other day then couldnt find the thread now i cant find the info typical i was looking for something completely different

 

Dennis

 

Did you ever find that stuff on my engine again? or will it have to wait for next years spring clean?

 

The original tread was titled "Ailsa Craig" - engine info wanted.

 

Cheers