Controllable pitch propellers for small boats ...

[kengrome]

I cannot seem to find a supplier of controllable pitch propellers for small boats and boats with low power engines. If anyone has a source that I can contact, please post it here, thanks!

[StianM]

What kind off power are you looking for?

If you ask Wartsila they will say low power engines is 5000hp.

If you ask Volvo they would say 100hp.

[Pericles]

Ken,

Brand new and British. It's my first choice. http://www.yellowfin.com/VSDTechnology.asp

Pericles

[kengrome]

What kind off power are you looking for?Only 10-50 HP.

[kengrome]

Brand new and British. It's my first choice.Hi Perry, I love the Yellowfin concept but when I talked with them they said they probably wouldn't have one for a small engine for a year -- and the guy sounded like it might be more like several years, not just one. I think they have their hands full with developing the bigger units (which obviously produce bigger profits) at the moment ...

[StianM]

Only I can think of

www.nogva.no

They might make something smal enough.
It seam like it was more normal to have CPP for that rating in the good old days

[Pericles]

Hello Ken,

The plans for the LB26 from Jacques Mertens arrived 15 minutes ago. Oh boy, oh boy, oh boy!

http://www.bateau.com/studyplans/LB26_study.htm?prod=LB26

However, I am going to the Thames Boat Show this morning, so no time for more than a quick study.

http://www.bealepark.co.uk/events_item.php?id=100

I'm building in marine ply, none of this prissy foam business for me. I am building a MAN's boat, so I can run down jetski riders with impunity. Make two or three passes with the Yellowfins at max depth and speed and nobody will find 'em.:D :D :D

As it happens, there aren't any flat chines specified, which might explain Jacques exhortations to keep it light and build superstructure with foam composite.

I purchased these plans , so I can consult http://www.ceproof.com/Marine/marinehome.htm in order to obtain the RCD certification.

All the best,

Pericles

[FAST FRED]

The engineering concept of a CP is grand but the costs would be way high for a small diesel.

50hp is 2 gph ,(with the finest engine at flank) gaining 20% efficiency will take a long time to recoupe $5000 in expenses for the CP.

Perhaps Rob White had the better idea, a prop system that allowed a rapid and easy no tool ,prop change , so the prop can suit the expected conditions.

FF

[TerryKing]

Hmmm.. Say we're talking about a pitch change of plus and minus, um, 30 percent, or so.

What would be the practical difference in efficiency if the same change in ratio was done in the reduction gear and the prop stayed the same??

I'm looking at multiratio drive systems...

[StianM]

There is alot of old CPP around where the pitch is changed by a mecanism going from the controls too the proppeler witch is simple and I asume cheap.

[FAST FRED]

What would be the practical difference in efficiency if the same change in ratio was done in the reduction gear and the prop stayed the same??

ZF has some fine (but hardly inexpensive ) 2 speed gear boxes that will shift underway.

The efficiency gains will need to be figured by the prop loading/rpm change.

Its a great concept as the prop can be sped up at cruise , boosting the load on the diesel at quiet cruise RPM , to give excellent cruising efficiency.

FF

[Pericles]

Hello Ken,

Update from yesterday

Went there yesterday. Fine weather. http://www.visitthames.co.uk/text/145/beale_park_thames_boat_show_2007.html

Two circuits of the lake in the Deben Lugger, commissioned by http://www.anglia-yacht.co.uk/ Keep an eye on the website for news.

One stand featured a S&G hull that demonstrated the speed with which a sailing boat can be constructed The results of 120 hours work is very encouraging. http://www.eventideowners.org.uk/

The Amateur Yacht Research Society http://www.ayrs.org./ is a great place for stick and sheet types to visit. A wide range of technical booklets are available as well as on e-mail discussion group.

How about the most cleverly crafted 6 person pulling gig? Ask Win at http://www.slipwaycooperative.co.uk/ for details and photos to be posted ASAP. The Bristol Jollyboat is delightful and the Steve Redmond designed "Wisp" on show, is light enough to be carried by one man.

The Selway Fisher stand was busy. http://www.selway-fisher.com/ and it was also good to see http://www.jordanboats.co.uk/JB/index.htm exhibiting a lapstrake double ended under construction.

A Polynesian styled catamaran signalled the whereabouts of http://www.wharram.com/
I was tempted to ask for an outing, but boarding her would have been a trial for legs that were stiffening up from all the perambulations around the show ground.

I counted at least 11 steamers of all sizes plus a huge r/c model of F106 complete with helicopter patrolling the lake as picket boat.

There were electric powered boats galore, even Helen Loney's 100mph world record holder electric hydroplane. http://www.conistonpowerboatrecords.co.uk/previous_years.shtml

The Boat Building Academy, based in Lyme Regis offer hands on short courses and a 38 week residential course. That' I'd love to send my youngest son to, but he is 2 years too young at present. http://www.boatbuildingacademy.com/

This synopsis of the stands I visited cannot do justice to a super day out. Not to mention the beer tent and the adjacent Hog Roast. I sampled Jordan, Squeaky and one whose name I cannot recollect as they were all washed down with Heritage cider, a strangely luminous, cloudy, orange coloured brew, but eminently drinkable. I was not the designated driver!

It's 12-30 on another warm sunny Sunday afternoon and I am tempted to undertake the hour drive there again. I just need to rouse the chauffeur from his pit. We'll see.

Regards,

Pericles

[kengrome]

Thanks for the replies everyone ...

I was hoping to find a small controllable pitch propeller not only for efficiency but more importantly for feathering and reverse without a transmission.

*IF* there were a small controllable pitch propeller available somewhere in the world designed to be driven directly by a common 3600 rpm industrial gas or diesel engine in the range of 4-20 HP, I can think of hundreds of small boat designs that might benefit from such a propeller.

Just think, no gearbox and no speed reduction needed, yet you still have F-N-R at all engine speeds. Instant reverse without shifting into neutral and without slowing the engine down. If it could be built and sold for $1000 I'm pretty sure there would be a huge global market for it, especially if the quality were good.

In the meantime, until someone actually builds one, I guess those of us who appreciate the economy and simplicity of industrial engines for our inboard power requirements will just have to use other methods to achieve our goals ...

[SeaJay]

Is this what you had in mind?

http://www.amartech.nl/English/awmpropellersE.html

[TerryKing]

http://www.boatdesign.net/forums/showthread.php?t=5063&referrerid=18850

talks about the Kitchen Rudder, which gives fwd-neutral-revers with NO mechanical parts in the drive train and no need for clutch or transmission...

Anyone seen a practical application of this in current use??

[Pericles]

http://en.wikipedia.org/wiki/Kitchen_rudder

http://www.propellerpages.com/?c=nozzles&f=Speed_Nozzle_Tests

http://www.boatdesign.net/forums/showthread.php?t=418&highlight=Kitchen+rudder

Hope they are of use Terry.

Pericles

[TerryKing]

Thanks, Pericles.. I will read the whole thread.. Good to see some actually using this in 'modern' designs.

This looks appropriate for designs up to, what?, 10 or 15 knots, maybe more on a larger craft. Sort of the range a Kort nozzle would work well for, perhaps.

It's all about shaped metal in relative motion to water, whether it's conventional prop/rudder with reverse rotation, water jet, or Kitchen Rudder/Drive. But I'd love to have the time to build a small boat with a simple small car/truck diesel, dry exhaust, closed cooling and 'almost no Marinization' .

How about a direct-drive surface drive with a 'rudder' that 'unfolds' above the water surface at planing speeds, but lowers to a Kitchen-Like configuration for low speed maneuvering, neutral and reverse?? No transmission. Maybe no CV joint if the mounting is just right... ??

It's all just to get water directed where we want it...

[thudpucker]

That's a lot of links to be read.

In the 1950's I used to rent an inboard skiff with a 5 or 6 Hp Briggs engine and dry exhaust.
It had a mechanically reversable three bladed Prop.

There was a Hub splined to the shaft.
The Blades rotated on studs mounted on the Hub. (I dont remember how the blades were fastend to keep them from flying off)

Each blade had a small lever attached. The end of the lever had a Roller that rode in a sleeve.
The sleeve was free on the shaft and it was moved in or out by a link to the shift lever up near the engine.

Moving the sleeve fwd rotated the blades to bite in and move the boat fwd.
The opposite for reverse.
All the strain was taken up by the splines and those rollers in that sleeve.

I could yank it from Fwd to Rev with no problem at all. The boat move along about Six to Eight Mph.

I've always thought a guy could mount that Prop shaft on a Strut that would slide up and down, along with its rudder.
That way if you ever had to go on the beach you could just pull it all up out of the way and have a slick bottom boat with no damage to the running gear.