Sealine S41 with KAD300s what Propellers work better for cruising

[Crownfibre]

Hi I am new in this Forum , last year I bought a Sealine S41 year 2001 with KAD300 on DPG drives that I reckon have 1.78 : 1 ratio. with C3 stainless propellers cruising 3400rpm at 22 knots , while top speed 29 knots at 3850rpm

I was told that the S41 with KAD300 should have the C4 sets propellers to cruise 24 knots at 3300rpm and would have a top speed of 31 knots at 3800rpm. Is this true and realistic?

Am I too low with C3? To be honest , fully loaded with fuel , water and 8 passengers it goes on plain really quick and easy without any hassle .

Can anyone who has an S41 out there with KAD300 reply please
Thanks
Clyde
Crownfibre

 

[Greg2]

Hi I am new in this Forum , last year I bought a Sealine S41 year 2001 with KAD300 on DPG drives that I reckon have 1.78 : 1 ratio. with C3 stainless propellers cruising 3400rpm at 22 knots , while top speed 29 knots at 3850rpm

I was told that the S41 with KAD300 should have the C4 sets propellers to cruise 24 knots at 3300rpm and would have a top speed of 31 knots at 3800rpm. Is this true and realistic?

Am I too low with C3? To be honest , fully loaded with fuel , water and 8 passengers it goes on plain really quick and easy without any hassle .

Can anyone who has an S41 out there with KAD300 reply please
Thanks
Clyde
Crownfibre

Starting a new thread on here might be better for visibility rather than tagging onto an old one.

Also worth trying the Sealine Forum if you haven’t already. A friendly and helpful bunch in my experience and there will be other S41 owners on there
.

 

[Forum Admin Team]

Posts moved (New thread).

 

[kashurst]

Boat speeds vary with load, underwater growth, sea state - all sorts. And it doesn't take much growth or slightly fuzzy props to slow them down.
I suspect you have the right props as the engines will hit max rpm and a decent speed. Every boat is different even between two of the same make and model. They are not like cars. Broker/Magazine articles/websites tend to be optimistic too.

Are you in tidal waters and are you measuring speed with GPS? And have you adjusted the legs and trim tabs to tune the ride angle? Take some weight off the boat and spend some time experimenting with the leg and tabs - you may well find your rmissing knot or two.

If you put props on with a steeper pitch to gain a knot or two you may find the engines struggle to hit max rpm. This is a very bad thing as it is overloading the engine, the exhaust gas temperature may get too high and they go bang. Better to leave a bit of head room than chase an extra 2 knots that you won't really miss. You won't save any fuel either as the required energy to move the boat won't reduce with different props.

The important number is not the speed the boat will do, it is it's ability to hit max rpm - and yours clearly does and readily.

Sounds like everything else is spot on if both engines hit 3850 rpm. So I would wait until the boat is next cleaned and antifouled underneath, roughly half fuel half water, take off some of the inevitable excess cargo and see what she will do then on a calm day to give you a reference. Adjust the legs etc and then you will see the max speed of your boat. Sounds to me like your boat is in great health.

 

[volvopaul]

Hi I am new in this Forum , last year I bought a Sealine S41 year 2001 with KAD300 on DPG drives that I reckon have 1.78 : 1 ratio. with C3 stainless propellers cruising 3400rpm at 22 knots , while top speed 29 knots at 3850rpm

I was told that the S41 with KAD300 should have the C4 sets propellers to cruise 24 knots at 3300rpm and would have a top speed of 31 knots at 3800rpm. Is this true and realistic?

Am I too low with C3? To be honest , fully loaded with fuel , water and 8 passengers it goes on plain really quick and easy without any hassle .

Can anyone who has an S41 out there with KAD300 reply please
Thanks
Clyde
Crownfibre

I am sea trialing one on the 23rd so I will come back to you .

 

[jon and michie]

Hi I am new in this Forum , last year I bought a Sealine S41 year 2001 with KAD300 on DPG drives that I reckon have 1.78 : 1 ratio. with C3 stainless propellers cruising 3400rpm at 22 knots , while top speed 29 knots at 3850rpm

I was told that the S41 with KAD300 should have the C4 sets propellers to cruise 24 knots at 3300rpm and would have a top speed of 31 knots at 3800rpm. Is this true and realistic?


Can anyone who has an S41 out there with KAD300 reply please
Thanks
Clyde
Crownfibre

I had a Kad 300 with DPG out drive and yes it had C4 Stainless Props but the ratio was 1:68