New propeller??

[doctormilner]

feathering prop

I decided to replace fixed 3 blade on my Grand Soleil 46.3 with a feather/folding prop a few weeks ago.
My research led me to the Australian Autostream 3 blade feather with ext adj. in stainless. Steel Developments ltd.
I can say no more as it is sitting in the back of car at present awaiting the next liftout.!

Cap'n Bob Black Pearl Charters


r

 

[Seanick]

From memory the Auto Stream will not handle 78HP.

You will need boat dimensions.....LWL, Beam, Draft, Keel type and displacement. Thats so they can guestimate your max hull speed.

From the engine you need to know max HP and at what RPM, I would also want to know revs and HP at 80% RPM.

Also gearbox reduction and type, propellor shaft size in mm if metric or inches if imperial-sounds obvious but the shaft tapers are different.

A note of current prop size (diameter and pitch) and performance will help too.

The advantadge of a feathering prop is that most have adjustable pitch, so you just go for the max diameter you can swing, Bruntons set the pitch and you can fine tune it over the next season.

What is your boat/engine?

My 4 blade 22" was about £2-3k (I have mentally blanked the actual cost!!)

 

[tel1]

From memory the Auto Stream will not handle 78HP.

You will need boat dimensions.....LWL, Beam, Draft, Keel type and displacement. Thats so they can guestimate your max hull speed.

From the engine you need to know max HP and at what RPM, I would also want to know revs and HP at 80% RPM.

Also gearbox reduction and type, propellor shaft size in mm if metric or inches if imperial-sounds obvious but the shaft tapers are different.

A note of current prop size (diameter and pitch) and performance will help too.

The advantadge of a feathering prop is that most have adjustable pitch, so you just go for the max diameter you can swing, Bruntons set the pitch and you can fine tune it over the next season.

What is your boat/engine?

My 4 blade 22" was about £3-4k (I have mentally blanked the actual cost!!)

hmm, mite have to wait a while then as i dont think i can get lifted before the boatshow, i dont know my current prop staus, i just know its fixed bronze 3 blade.

in response to the boat its a moody 38, gearbox is a hurth 2:1 i believe. it used to have a perkins prima m50, i replaced it with a 2nd hand but unused volvo tmd22. they are almost the same engine, the main difference being the 28hp which comes from the turbo.

im going to do long distance cruising and i think i should invest in a folder as id sooner sail round the world. "motoring around the world could become expensive!"

in terms of perfomence, at 1900 rpm with the original prop im getting 6kn in slack water.

i just done 60 miles two days ago with the engine at 1900rpm and i used roughly 20, 25 lires of fuel. haveing a busted fuel gauge when i first bought the boat i can compare this to the old engine. dont know if you think its good or not??

one thing i do know though is at 2500rpm she drinks fuel like i drink beer, i done 2500rpm for about 8 hrs and she drank about 70 litres!

 

[tel1]

haveing a busted fuel gauge when i first bought the boat i can compare this to the old engine.

"i CANT compare this"

 

[Quandary]

Prices

Tel -From the Ym report * designates folder, the others feather or are fixed
the first figures are price range last figure is the price as tested (I have lost the columns in posting)
Autoprop (Brunton) £1,480 upward (as tested) £1,620
Autostream 3 blade £2,050 - £2,460 £2,095 (fixed prop)
Axiom £590- £1230 £690
Featherstream 3blade £1,130-£1,680 £1,150
Flexofold 3*blade £1,485-£4,075 £1,690 (from Darglow)
2* £705- £1,605 £885
Gori 3* £1,840- £6,900 £1,840 (from Silette)
Kiwi 3 all sizes £985
Max Prop 3 £1,795 - £16,405 £2,065 (from Darglow)
2 £1,120 - £2,750 £1,275
Slipstream 3* £1,360 - £1,845 £1,530
2* £895 - £1,195 £990
Varifold 3* £1,604-£2,470 £1,770 (from Brunton)
2* £585- 760 £ 630
(some are dearer than an engine but the Flexofold and Varifold 3s seem good performers for the price if you can get it big enough)
Hope this helps you decide which to look at.

 

[Seanick]

Quandry, I can't thank you enough, it seems I have tourturing myself and thinking I spent more than I did.
I think I have attatched this years price list.

The OPs' choice is limited by the large HP. Kiwis max 55HP etc etc.

It will be tricky getting the pitch right with the turbo......Although you could use a folder I would go for a featherer because you can adjust the pitch.
Best to note gallons per hour rather than MPG!

You made need something like a 19 x 11 3 blade with 33% DAR.

 

[tel1]

Quandry, I can't thank you enough, it seems I have tourturing myself and thinking I spent more than I did.
I think I have attatched this years price list.

The OPs' choice is limited by the large HP. Kiwis max 55HP etc etc.

It will be tricky getting the pitch right with the turbo......Although you could use a folder I would go for a featherer because you can adjust the pitch.
Best to note gallons per hour rather than MPG!

yes, i knew my engine was going to be a problem. and im starting to think of the price to. cruising means cruising, so speed isnt an issue, really. allthough the extra knot would be nice.

for the money of the prop, depending on what one i get, i could get a nice new liferaft and epirb which are still on my list. and they come under essentials as the prop would just be nice.

 

[tel1]

i cant do gallons, everything i do is litres!!!

 

[Seanick]

i cant do gallons, everything i do is litres!!!

Ahh the yoof of today!

Seriously though, you need to keep that engine under load or you will glaze the bores and soot up yer turbo. Therfore you need the right prop. Its best to be a bit overpitched than under.

 

[tel1]

Ahh the yoof of today!

Seriously though, you need to keep that engine under load or you will glaze the bores and soot up yer turbo. Therfore you need the right prop. Its best to be a bit overpitched than under.

dont get me wrong, it may sit at low revs when on for long periods, but i aint shy on the throttle, she gets a good blast for a while to clear the **** out of her! could i not get the origanal prop re pitched?

totally defeats the object of the folding prop but like you say, i want the best out of the engine. saveing fuel is at the top of my list.

starting to wish i took lots of prop and shaft pics now!

 

[Seanick]

If your current prop is in good nick you can repitch 1" either way....unless its already been done.
If you want to sail better in light airs its worth every penny. Might save you a day or two across the pond.....you may miss the storm and you won't need your liferaft!!

 

[tel1]

If your current prop is in good nick you can repitch 1" either way....unless its already been done.
If you want to sail better in light airs its worth every penny. Might save you a day or two across the pond.....you may miss the storm and you won't need your liferaft!!

well thanks for your advice, especially seanick! going to have to get that ym may issue thats on the boat, and im going to get a quote for sure. see what damage will be done to my bank.

one more final question, can you still fit a rope stripper if you have a fancy folding/feathering prop? its something else thats on the list. years ago i done lots of sailing around the spanish coast, they love to put lots of nets out! or they did in them days!

 

[Tranona]

totally defeats the object of the folding prop but like you say, i want the best out of the engine. saveing fuel is at the top of my list.

Well, you are going to struggle to get fuel economy with the engine you have chosen. It is way too powerful for your boat and turbos are rarely used (not at all these days) in yacht auxiliaries. Volvo used to supply them but stopped quickly because of the problems they encountered with the narrow power band and keeping the turbo cool.

The original 55hp engine was at the top of the power requirement - a 40hp engine is more than adequate. Fuel consumption is a function of the power produced by the engine and absorbed by the propeller. Your boat needs about 30hp for cruising, so if you look at the power curve of your engine that will probably equate to about 1600 rpm well below its most efficient band.

A Bruntons may help because it alters its pitch in relation to the load on the engine and speed of the boat. However, no propeller will offset the basic problem of an over engined boat.

Just to illustrate what I mean. Using the Propcalc programme and 3 bladed prop

40hp engine prop size 16*12 max speed 7.76 knots
55hp engine prop size 17*12 max speed 8.04 knots
78hp engine prop size 18*12 max speed 8.04 knots

So for double the power and double the fuel consumption you are getting about quarter of a knot extra speed! The 55hp naturally aspirated engine is a good compromise so it is not surprising that was the engine fitted as standard.

Yes, you can fit a ropestripper see www.ropestripper.com for full information

 

[tel1]

totally defeats the object of the folding prop but like you say, i want the best out of the engine. saveing fuel is at the top of my list.

Well, you are going to struggle to get fuel economy with the engine you have chosen. It is way too powerful for your boat and turbos are rarely used (not at all these days) in yacht auxiliaries. Volvo used to supply them but stopped quickly because of the problems they encountered with the narrow power band and keeping the turbo cool.

The original 55hp engine was at the top of the power requirement - a 40hp engine is more than adequate. Fuel consumption is a function of the power produced by the engine and absorbed by the propeller. Your boat needs about 30hp for cruising, so if you look at the power curve of your engine that will probably equate to about 1600 rpm well below its most efficient band.

A Bruntons may help because it alters its pitch in relation to the load on the engine and speed of the boat. However, no propeller will offset the basic problem of an over engined boat.

i totaly agree, but the choice of engine was a difference of around 8k to 10k!

i think many people would of done the same when it came down to my problem!

i do like your last comment on brutons though, dident know it alterd pitch in relation to load. that may have just made my mind up!

 

[Seanick]

OK, so look at a Bruntons AUTOPROP, not a VARIPROP (featherer)

Price list on my last post.

 

[Tranona]

totally defeats the object of the folding prop but like you say, i want the best out of the engine. saveing fuel is at the top of my list.



i totaly agree, but the choice of engine was a difference of around 8k to 10k!

i think many people would of done the same when it came down to my problem!

i do like your last comment on brutons though, dident know it alterd pitch in relation to load. that may have just made my mind up!

But you are just about to spend nearly half of that on a new prop! Seriously, don't know how you got to that price difference unless your 78hp was free. A new 50hp Beta or Nanni complete would have been less than that in total and much more appropriate to your boat. I think you will be paying for your "economy" decision for the rest of the life of the engine.

All you can do is prop it so that it runs at sensible revs and accept that you are wasting power and fuel. You may already have discovered the other downside of overpowering and that is high speed at tickover revs which can make maneouvering a pain.

Incidentally, my Bavaria 37 (wash my mouth out) has a Volvo 2030 and has never felt underpowered, cruising at 5.6 ( and less than 2 litres an hour) and top of 7.6 and a dream to handle at low speed.

 

[Seanick]

Wow, less than 2 litres/hr! Those Bavs are truly wonderful!

Agree though. Change the engine for as Tranoa says you are way over powered. Whip it out and stick it on Fleabay. It will be cheaper in the long run. You have more HP than me, and my boat is 37 LWL, 14' beam and weighs 18 tons!



......and we still overtake modern 40'ers!

 

[tel1]

Wow, less than 2 litres/hr! Those Bavs are truly wonderful!

Agree though. Change the engine for as Tranoa says you are way over powered. Whip it out and stick it on Fleabay. It will be cheaper in the long run. You have more HP than me, and my boat is 37 LWL, 14' beam and weighs 18 tons!



......and we still overtake modern 40'ers!

ive only just put it in!!! and if anybody else has a moody 38 they will know how hard it is to get the dam thing out!

it was that much cheaper as it was a straight swap, and i done the majority of it myself, saveing loads on labour.

it definatly wont come out, and i may not change the prop. yea all of your points are true, but going past the goodwin sands in 3 metre seas and 20kn on the nose my enginge ploughed me through at 6kn at 2500 rpm. my old engine would never of done that. i feel safer knowing that if i do get caught out in anything, ive got the extra umph there if i need it.

and you are right in marinas, the slowest it goes is 2kn in tickover, but then thats what neutral and reverse is for. plus it helps being able to control your boat, which i can do, so going in to a berth a 2kn does not phase me.

 

[tel1]

not only that, the money i save will go on the prop, but whatever engine i had it would still need to be bought, so i wouldent of saved anything if i got the so called "rite engine".

fuel consumption doesent bother me to much, like ive said, i wish to sail around the world, not motor!

 

[Tranona]

not only that, the money i save will go on the prop, but whatever engine i had it would still need to be bought, so i wouldent of saved anything if i got the so called "rite engine".

fuel consumption doesent bother me to much, like ive said, i wish to sail around the world, not motor!

But its not just the nearly double the amount of fuel you will use, and the cost, but you have effectively halved your range. And if you think it was difficult to get your engine out, wait until you have to get at the fuel tank! Not that there is any space to fit an extra or larger tank.

If you are using 2500 revs to get 6 knots then you are using a lot of power and fuel for the speed which is not surprising if you are using the smaller prop from the smaller engine. Very inefficient, but if you propped it correctly, revs would fall and the engine would never work in its efficient range and you tickover speed would be even higher!