Hi Guys,
I have my little 5.5mtr sailfish cat powered up by 2020 model DF70A Suzuki outboards. I have the standard Suzuki 13.7/8 x 15p 3 blade Aluminium props.
I am able to get the RPM up to 5600 rpm WOT when loaded up with all the gear, 300lts fuel, esky etc etc> I do have some ventilation issues in messy chop when the motors are trimmed. I can only get to about half trim in dead flat conditions.>
I recently tried some Solas 4 Blade 13.25x 15p in stainless. The props gripped better in turns, the engines felt smoother and the boat didn’t porpoise as much when trimmed. I like the extra stability they seem to provide.
I can rev to 5900 now and can trim to hit the rev limiter.
I was expecting a little more speed or more meters per litre with the 4 blade but at a given speed I have to rev faster and in turn more fuel is being used.
Im going to try a different set of props. I know it’s a bit of a black art this prop business. It has been suggested I try a 16inch pitch set of SS Props. But the additional inch is only 6.6% difference in drive.
Do you think it will be enough to at least match my speed and fuel consumption figures in getting with the 3 blade props or should I jump to 17 inch pitch first up and then come back if I need to.
I have to get some improvement in either cruise speed or fuel use at a given speed . Range is so important to me. My average fishing trip is between 220km and 360km round trip.
I rarely run the engines over 5000rpm. Most of the time Im cruising between 4100 and 4900 rpm
what are your thoughts?
|
Orig Suzuki Prop 3 blade 15p |
Solas SS 4 Blade 15p |
|
Rpm port |
Rpm stbd |
Km/l |
Rpm port |
Rpm stbd |
Km/l |
35kph |
4000 |
4050 |
1.9 |
4350 |
4300 |
1.79 |
40kph |
4500 |
4500 |
1.7 |
5100 |
5200 |
1.33 |
|
|
|
|
|
|
|
45kph |
4950 |
4900 |
1.6 |
5500 |
5550 |
.98 |
|
|
|
|
|
|
|
49kph |
5400 |
5400 |
1.06 |
5800 |
5900 |
.98 |
|
|
|
|
|
|
|
51kph |
5600 |
5600 |
1.03 |
5900 |
5900 |
1.0 |
55kph |
5650 |
5700 |
1.11 |
|
|
|