New Propeller Results, Long Winded/ Read

[Luvit]

Some may have seen that I have been testing some new props to see if I could get better mid range speed and fuel economy. 

The motor is a 100HP Yamaha 4-stroke 2006 model with around 600 hours on it. The standard prop I'm told was not a great design and an aftermarket one would improve efficiency. I bit the bullet and purchased a Solas Prop from Kawana Waters. Based on the information I provided they suggested a 13.5" x 15P (degree pitch). I tried this and although it was an improvement it was not enough for my liking based on the the cost of the stainless prop. Solas have a performance guaranty so you can keep swapping the props until you are happy. 

To save on postage costs I drove back down and swapped it for the next size pitch up a 16P. I didnt find much different from the 15P. So they then said to lift the motor by one hole and see if it held in without cavitating on turns and to remove the hydrofoil for testing.

Each inch of pitch you go up should reduce the rpms by 200rpms. The recommendation for the my 100 HP is to have at WOT (wide open throttle) the revs between 5000-6000. After testing I was still exceeding the max rpm at 6100.

So I took the boat down for them to look at it, they said that because of the design of the step up transom the motor could be lifted possibly another hole but to test a 17P prop. 

Unfortunately it was too rough the day Danielle and I went out to get the boat up to full throttle and with out the hydro foil the boat would stand the bow up.

So when we got back to the Pine river I dropped it in and at WOT the motor hit 5800 rpms, perfect. It was taking a little longer to get out of the hole without the hydrafoil so I went home refitted the hydrafoil and retested it this morning. With the hydrafoil fitted I lost approximately 2kmph over some of the rev ranges. However I'm happy for that if the boat bows rides lower.

So after this exercise there has been an increase in speed over all rpms ranges but most notably where I wanted it was the mid range from 3500-5800. Compared to the old prop it is a minimum 10 kmph faster at the same rev ranges and the WOT is now 5800.

The summary is, that it can now achieve the same speed as the old propeller at 500 rpm less. The mid range cruising should provide better fuel economy and at WOT I'm am getting a higher top end speed. The top end speed will be due to the lifting of the motor than the new prop though.

So the only thing now is to do a decent trip and see what the economy is. The best I used to get from  the old prop in good conditions was 1.8-1.9km per litre of fuel. With the 15P prop that was on when Brian and I went out in crap conditions it achieved 2km p/l. 

The aim was to save 15% fuel by making the changes which will mean over my 120 litre fuel tank, saving 18 litres per tank and 2 less 10 litre Jerry cans to carry on board. More space in the boat!

I will up date this thread when I have done a trip to see what the actual fuel economy is and report.

 

 

 

[Arod]

Interesting to see how this goes, as I'm about to go through the same exercise myself.  What speed was it pulling at WOT on your run in the pine?

I've got a f115, but same hull so keen to use your numbers as a benchmark on speed.  Still just running the stock alloy, which will hit the limiter when trimmed out and isn't hooking up that well through the top end of the revs hence the need to do something. Fuel wise it's ok, sitting at a cruise of 27-28kts it'll get 2.6-2.7 km/l, at 35kts it drops to 1.7km/l.  

[Luvit]

Original prop the tacko was saying 6100 but now 5800 with new prop. I don't have any fuel flow meter  on board I just take it for a run and fill it up at the end of the day to see what has been used. Divide the total kms traveled by the litres of fuel used. 

I lifted the motor another bolt hole this morning and will test again to see if improves again. This is the last test because There are no more holes to lift it.

[benno573]

Thanks for putting this one up Wayne, interesting read.

 

my engine is deliberately "over propped" to increase speed at mid-rev range. At WOT mine will hit 5200rpm, rev limiter is at 5500 so close enough. I suffer the same problem with a bit of slowness punching out of the hole initially though.

 

out of interest... What did they sting you for the prop?

[Luvit]

I picked the propeller up from Kawana Waters so saved on postage.

Cost of the stainless propeller was $640. Normal cost with free delivery is $695

Being able to swap them over and keep testing is great. There was no hassles when I swapped them over. It was bit like a partnership with you doing the work and testing with their guidance.

[Luvit]

OK The results are in.

Except in a rush to test the old prop I backed the boat down in the afternoon and launch it, however I forgot I'd taken the bung out after the morning test! So the low end of the old prop results will not be accurate and I will test again eventually. Mind you the mid to top should be OK because the water would have been dispelled when underway at speed.  

I really thought lifting the motor to the highest setting would see an improvement in performance but I was wrong. The best performance for my boat with the Hydrofoil on is one hole down hole 3 on the motor bracket. 

It is a time consuming exercise but once it is done you know you have the best performance.

Now to test the increase in economy.

Solas Propeller test results .xlsx

Solas Propeller test results .xlsx

[demarc]

Have you been doing your tests with normal weight for a days fishing on boat? 

[Luvit]

8 minutes ago, demarc said:

Have you been doing your tests with normal weight for a days fishing on boat? 

Full tank of fuel and normal stuff on board. Another person would have been handy but an additional 100kg shouldn't be to big a deal.

[demarc]

4 minutes ago, Luvit said:

Full tank of fuel and normal stuff on board. Another person would have been handy but an additional 100kg shouldn't be to big a deal.

Good work. 100kgs shouldnt at all. Im at near 600 on board weight for my 1770 trips, so need new prop just for that. Watching your experiences with great interest. Last i herd solas stopped the exchange program, but you're the second person to confirm thats not the case. Thanks. 

[Luvit]

When I did the Kimberly trip we had a prop for heavy load. 650 litres of extra  fuel on board. 

Once we unloaded the fuel on an island we changed props back to a more economical cruising pitch.