G'day crew,
I am replacing the engine in my 34 ft Vande Stadt, with a Yanmar 3YM30 going in. I have no intentions fo entering races ( even around the bouys in the harbour isn't for me), I use the boat regularly for trips way and simply need a reliable engine with enough grunt to help me along when conditions might require a motor sail or simply get me home when its crap. The rotation on the existing motor is LH and the new engine is RH rotation, so the prop needs to be replaced. I understand the designs and advantages of folding and feathering style propellors, and being a cruising sailor, I am not overly concerned whether I lose half a knot in my tacks. It is my intention to use the existing 25mm shaft, and I will of course replace cutlass bearing whilst changing things out. Engine position, size and bed will accomodate the replacement with no major installation issues. I've inherited a 16 x 12 RH 2 blade prop and am seeking any tips/ advice from others who have undergone a similar exchange and had to replace props in the process. If it is possible to utilise what I've got (without re creating the wheel so to speak) then I will of course head down this road.

Check out your gearbox first.

Plenty of online prop calculators to let you know if you're in the ballpark with that prop. You also need to know if the prop taper matches the shaft.

Cheers, Graeme

At a guess the 16 x 12 could work if your gearbox is a 2.5 to 1 or 3 to 1.
You might be ok with this pitch as a starting point. But you will need to achieve the full rev range when you do a sea trial.
In Tassie you may need the grunt to motor off a lee shore in a blow and an over pitched prop will stall.
Work out how many revs you do achieve with this prop at full throttle and phone Porters in Sydney with all your info. Glen can work out what pitch you need to achieve your goal and can re pitch your blades to suit.
Also make sure you have at least 1.6" or more clearance of the 16" diameter prop to the hull.

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Ramona said..
Check out your gearbox first.

You may have a Kanzaki gearbox which is a cone type box. The ratios between forward and reverse may be different. I would suggest you check first whether the existing propeller will work with the gearbox using reverse as forward. Volvo cone boxes have the same ratios and can drive either way. I would check before spending any money.

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Ramona said..

Ramona said..
Check out your gearbox first.

You may have a Kanzaki gearbox which is a cone type box. The ratios between forward and reverse may be different. I would suggest you check first whether the existing propeller will work with the gearbox using reverse as forward. Volvo cone boxes have the same ratios and can drive either way. I would check before spending any money.

Hi Ramona,
Yep its all Kanzaki and yes, the ratio's are different. The KM2P-1 does have a different ratio for ahead / astern (2.26/3.06) Standard Cone clutch set up with clockwise rotation.

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wongaga said..
Plenty of online prop calculators to let you know if you're in the ballpark with that prop. You also need to know if the prop taper matches the shaft.

Cheers, Graeme

Cheers mate, I've delved into a few of those online calculators just now. Thanks for the tip about the prop taper on the shaft as well - one of the reason I thought to ask the questions on the forum as I know a bitabout this but def not everything and am no scared admit it. Cheers

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Ambler said..
At a guess the 16 x 12 could work if your gearbox is a 2.5 to 1 or 3 to 1.
You might be ok with this pitch as a starting point. But you will need to achieve the full rev range when you do a sea trial.
In Tassie you may need the grunt to motor off a lee shore in a blow and an over pitched prop will stall.
Work out how many revs you do achieve with this prop at full throttle and phone Porters in Sydney with all your info. Glen can work out what pitch you need to achieve your goal and can re pitch your blades to suit.
Also make sure you have at least 1.6" or more clearance of the 16" diameter prop to the hull.

Ambler,
Thanks for the tip on the hull clearance, one of the things I did check and yes there plenty of scope there.
Cheers