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Old 08-27-2015, 09:54 PM   #1
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Default smallest prop

Hi All

I have a Maxum 2300 SC with the V8 5.7L Mercruiser engine and the Alpha 1 Gen 2 outdrive.

I have it on the Thames and with really limiting speeds (8kph) I was hoping to replace my prop with a smaller one.

To be honest I don't know exactly what is on there now but it is a fairly standard one.

Is someone able to advise what is the smallest prop (or reasonable small and suitable for rivers) for low speed trips up and down the river?

Thanks
G
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Old 08-27-2015, 10:40 PM   #2
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G welcome aboard

What speed do you normally run at?

Not sure I understand what you mean by smallest prop, diameter or pitch?

If you looking for a prop that moves the boat further at a low rpm that would be a prop with a higher pitch.

If you want a prop to let the engine turn higher rpms with less speed then lower the pitch.

IMO the boat works best with a prop that allows the engine to achieve its WOT.
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Old 08-27-2015, 11:02 PM   #3
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Hi

I am looking for a
Quote:
prop to let the engine turn higher rpms with less speed
So yes a lower pitch but also perhaps a smaller blade size etc.

The boats min speed at the moment is probably about 6kph and would like to reduce that somewhat if possible.



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Old 08-28-2015, 12:52 AM   #4
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G, I hear what you are trying to do. If you get a smaller prop your maneuvering is going to suffer. I've sailed over in your neck of the woods and would want all the torque I could get with a power boat when Mediterranean mooring. Go too much slower and you will start to lose steering all together. Is your speed limited everywhere you go, or just a portion of your trip? If all the time I would look into mounting a small kicker outboard somehow for all your slow speed trips. Would save you a bunch in gas with a little 9.9hp or a 15hp outboard.
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Old 08-28-2015, 01:32 AM   #5
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I gotta agree with deltaV going that slow against any current or wind and steering will be comprised. A kicker would be the way to go.
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Old 08-28-2015, 07:36 AM   #6
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Right, I was under the impression I would have more control - at least slower moving control with a smaller prop.

Coming into mooring is really tricky as you need to take the throttle off to slow down so get no steering at all at times...
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Old 08-28-2015, 02:05 PM   #7
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Thanks for the info, I don't think a kicker would be an option for me, Ill just look at getting a prop with a lower pitch, it will help a bit over what I have.

Can anyone recommend a specific place in the UK (preferably in Surrey) where I can get props or will a local Chandlery just be fine?

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Old 08-28-2015, 08:51 PM   #8
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Most chandlery' should be able to help you out. Across the pond here it is common to allow the customer to test drive a new prop. Hopefully you can find a place that will let you do that. I suspect your local marina may be able to point you in the direction you are trying to go, as what you are trying to do, may be a normal thing over there. Have not met one person on the water that wishes their boat was slower over here. I operate a 34 foot Donzi for work with twin 300's and it is too slow, ha. Wish you luck and let us know how it goes!
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Old 08-31-2015, 01:22 PM   #9
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8kph would work out to around 4.3 kts (nautical miles). You should have plenty of steerage at no wake speeds. Bow wonder is a natural phenomenon and is curbed by getting used to not over steering.

To hold a straight line; once the boat starts to wander left, you turn right. Once the boat starts to respond by turning right, straighten the wheel. Basically, turn until the boat starts to turn, then straighten again. You'll find you're almost wagging the wheel left right over and over and going straight.

If you turn until you're aimed in the direction you want to go, then straighten, you'll continue the turn well past your desired heading.

A smaller prop for no wake speeds won't fix that. Only handling will.
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Old 09-15-2015, 12:57 PM   #10
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Hi Shrew

thanks for the info, I was wondering about the constant steering and was going to raise a separate thread about it - may still to get more specifics on what can be done - as well as how to tighten the steering as there is reasonable amount of play in addition which does not help matters.
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