Pitch on yamaha K series propellers

C-NUMB · 13 October 2013, 17:23

On my SR 5.4 (90 YAM) a yamaha K series 19 inch ali have so far worked OK.
The sweet spot has been in calm seas abt 4200 rpm, speeed 28+ knots and according to fuel flow abt 22-23 l/h. Handling ok, but grip is not always perfect and need to be trimmed out pretty much.

Today tested a black max ali prop, also 19. got approximately same speed and consumption with 3800 rpm, prop seams a bit too high pitched for my usage, and struggled to go over 4600 rpm. So it seams like there is a significant difference in the actual pitch on either the Yam or Mercury prop. Wa

It was choppy seas so did not get a clear picture but by the feel, seams like there is slightly more bow lift on the black max, less need for trimming out.

Anyone else noted similar pitch "errors" on the K series props?

Kat1nka · 13 October 2013, 19:56

Hi,

what is the diameter for both props ? There could be an explanatory difference ?

Landlockedpirate · 13 October 2013, 20:18

There is a lot more to a prop than just the pitch and diameter. Shape of blade, the amount of cup, the length of the hub etc etc.

I would use the prop you feel suits you best.

C-NUMB · 14 October 2013, 04:52

They are both 13X19. For sure there is a lot of differences but 400 rpm is unusual much as both are standard ali propellers. In the Black Max range guess the 13 x 17 would be better for my needs, the K19 is not bad either.

captnjack · 14 October 2013, 06:59

A tiny difference in diameter will easily manifest as 400 rpm difference. Despite all the talk here about pitch, for my prop selections over the years, diameter ends up being a far more critical variable.

C-NUMB · 14 October 2013, 11:22

Quote:

Originally Posted by captnjack

A tiny difference in diameter will easily manifest as 400 rpm difference. Despite all the talk here about pitch, for my prop selections over the years, diameter ends up being a far more critical variable.

That is probably the case. Then will give it a kiss with the angel grinder, style" ballistic" to sort the diameter...No, only joking

In fact I have 17 ballistic that will try out when having the time, interesting to see how that will perform.

9D280 · 14 October 2013, 12:27

+1 for the diameter.

Also rolled in there is the engine's top end torque......

Nos4r2 · 14 October 2013, 16:46

And the thickness of the leading edge of the blade.

I've been using Michigan Wheel Match props on my Yam for a few years. They've got a sharper leading edge than standard Yam props, and they pick up a bit better.

Kat1nka · 14 October 2013, 18:00

Hi,

searching for the right propeller seems to be really difficult. My boat came with an old scuffy Yamaha 12 5/8 x 21 with a topspeed of 42 - 43 knots but reaching only 5300 rpm at WOT and offcourse some chine-walk. So trial and error began, with a 13 3/8 x 19 Ballistic I lost a few knots topspeed but gained a faster hole shot leaving WOT at only 5100 rpm. Then we checked the 21s diameter and discovered that it was some kind of special propeller for light boats. My SR 4.7 weighs 250 kg + 122 kg for the Yamaha 90 and then some fuel etc leaves me at 400 kg ? which I guess is a light boat

.
Next a friend borrowed a 20 inch Laser II, which behaved a little odd. Back in the harbour I found the explanation: the propeller was 22 inches.
The 4-blade Solas was really fun to drive, but topspeed left a little to desire, 38,5 - 39,5 (downwind)... So the search goes on, next in line two steelpropellers, 17 & 18 inches.
Any suggestions for propellers or do I have to accept that a 21 inch aluprop is the best for my boat ? I am trying to reach 5600 - 5800 rpm at WOT and a good grip + topspeed. I havent started to play with the engne hight yet. The cavitation plate is about level with the bottom, so it could be higer ?

Test table:

Alu Steel Steel Steel
Yamaha Solas Laser 2 Ballistic
RPM 12 5/8 x 21 4 x 13 x 17 13 x 22 13 3/8 x19
2000 14,7
2500 15
3000 20 19
3500 25,7 25
4000 30,5 28,7 36
4500 35,3 32,5
5000 39,3 36
WOT 42 - 43 38,4 - 39,3 39,7 41,3
RPM 52- 5300 53- 5400 4400 5100

Stoph · 16 October 2013, 08:57

Had a similarly frustrating experience this summer myself after my yam 70 had an argument with something solid and made an interesting shape of 2 of the blades.. Prop was a yam k 13 1/4 x15 and totally unmarked...wot with my normal load was 5500..right in the middle of the rec 5-6k only replacement i could get at short notice was a Michigan wheel..quoted at same size and pitch but when fitted wot way down at 4800 and acceleration none existent..was convinced i had lost 20hp somewhere! Had the original yam prop rebuilt and put that back on and wot 5500 again with driveability 100% better...slight difference in blade shape/area seems to have had the same effect as 3 inches more pitch! Slightly annoying when sold as an equivalent replacement for the original Yam K series! Still...its back in the box as a spare, and i haven't got to go looking for my missing power!

C-NUMB · 17 October 2013, 06:56

Quote:

Originally Posted by Stoph

Had a similarly frustrating experience this summer myself after my yam 70 had an argument with something solid and made an interesting shape of 2 of the blades.. Prop was a yam k 13 1/4 x15 and totally unmarked...wot with my normal load was 5500..right in the middle of the rec 5-6k only replacement i could get at short notice was a Michigan wheel..quoted at same size and pitch but when fitted wot way down at 4800 and acceleration none existent..was convinced i had lost 20hp somewhere! Had the original yam prop rebuilt and put that back on and wot 5500 again with driveability 100% better...slight difference in blade shape/area seems to have had the same effect as 3 inches more pitch! Slightly annoying when sold as an equivalent replacement for the original Yam K series! Still...its back in the box as a spare, and i haven't got to go looking for my missing power!

It looks like in many cases when changin to another brand with equal reported pitch/diam from K-series, it is likely to have a drop in RPM. So guess can be a good idea start testing with a pitch smaller then the one on th K series.

willk · 17 October 2013, 09:13

Quote:

Originally Posted by Nos4r2

I've been using Michigan Wheel Match props on my Yam for a few years. They've got a sharper leading edge than standard Yam props

PIGN isn't going to like that!

Nos4r2 · 17 October 2013, 15:51

Quote:

Originally Posted by Stoph

only replacement i could get at short notice was a Michigan wheel..quoted at same size and pitch but when fitted wot way down at 4800 and acceleration none existent..

Exactly which Michigan Wheel was it? There's a few types. I've always used the Match range. They're fantastic, but they're a bit hard to get now. The newer 'flowtorq' type ones look a bit different.

Quote:

Originally Posted by willk

PIGN isn't going to like that!

It's ok, I've fitted it with hammerheads on the blade tips so now it just bludgeons swimmers to death. PING?

Stoph · 19 October 2013, 20:53

From memory it was a Michigan wheel vortex... Quite noticeably different in shape to the k and that was reflected in the performance!

C-NUMB · 17 August 2014, 17:04

Today tested the prop i forgot for ages in the garage, a SS 3 blade Ballistic 13,5 X 17 on my SR 5.4.

it was kind of OK....
- on low rpm, speed limit area (aprox 5 knots), it seams to give a slightly better speed than any of the ali k series i use/ 17 & 19 at same rpm.

- in sharp turns, it looses temporarily grip, but will bite again as soon going straight
- top speed was a surprise, did 38 knots at 5800 rpm with two on board, 80L fuel + anchor, chain and other equipment, that's slightly better than by previous props with such load.
- when return from my trip today it was kind of chop, but it did not loose grip.
- definitely worked much better than the 19 black max.

My navman fuel flow censor needs the yearly lubrication so it was showing too low values, thus can not compare consumption with the k series.

As the RPM went that high, think would need little higher pitch. Will try the ballistic 19 but don't expect too much, think its too steep.

Nos4r2 · 17 August 2014, 17:32

From memory, your max recommended RPM is only 5500 so you're probably ok to go up to 19" pitch.

C-NUMB · 18 August 2014, 06:12

Quote:

Originally Posted by Nos4r2

From memory, your max recommended RPM is only 5500 so you're probably ok to go up to 19" pitch.

Yes, you are right, max is 5500. The 19 has a slightly smaller diameter, 13.3/8 compared to 13.5 on the 17 pitch so there is hope it would work. But i remember some one here mentioned a 19 ballistic is sluggish on this combo so let see how it goes, ill try it out next weekend.

C-NUMB · 21 September 2014, 16:42

Tested the 19 ballistic this weekend. Kind of mixed feeling. Think lightly loaded will
break 40 knots with this one easily. It did not loose grip in sharp turns like the 17 ballistic.
On the other hand(like the 17) it dos not manage much of trimming out, think the
K series ali is no worse.

2 adults, 90 l fuel and camping gear+food for the weekend, wot was just shy of 38 knots,
but max rpm was only about 4800 so the gap to the 17 is huge, this 19 its defo over pitched to my normal usage.

Not much bow lift in the Ballistic props, think the SR hull would benefit from that in easy
sea conditions and following seas, at least mine tends to go with a relatively long waterline. Latest tests have done with engine little higher than i used to so that possible also affect trimming.

maybe should test a Yamaha k series SS prop. Or then just going back to 19 ali, its a good alrounder....

C-NUMB · 30 October 2014, 14:24

Played little around with the SR 5.4 today. I have a 4 or 5 inch setback don't need for anything else so installed it on the SR. Then lifted the engine a inch or two. Did a picknic trip so was not particularly light loaded but was alone. On the return leg started to test how much can get out of my SR 5.4....

With the spare fuel, equipment bag and anchor close to the bow as usual, just mad a new speed record(for me) at 40,1 knots, aprox 5100 rpm.
- moved spare fuel and bags to the stern= 41,3 knots
- moved also anchor and chain, everything close to stern 42,3 knots 5200 rpm, not bad.
GPS speed, no currents here so its pretty reliable. Neither engine or prop is tuned, just as is.

Did not note any adverse effects by lifting the engine or the setback, but guess in heavy seas from the bow would need more weight to balance the boat. In following seas it would be better than without setback. It sounds that engine noise is less, no idea why, possible the ali is absorbing vibrations?

Still think the 19 is too steep, have a 17 pitch 4 blade will test next....