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Old 11 January 2008, 09:02   #1
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Best Engine HP for Skiing

Hello all:

Have a client that wants to buy a 420 Sib, he want's to ski:

The Sib Configuration is

Lenght 4.20
Wide 1.95
Pontoon 50
Aluminum floor
Sib weight 100 Kg
Skier weight 80/90 Kg

His intention is to ski with max 3 persons, 2 on boat (driver + counterweight on prow seat) + skier. Have no experience with skiers, what would be a nice 2 stroke engine to power this Sib boat: 30 or 40 HP ?

Any suggestions/comments/experiences are welcome

Happy Boating
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Old 11 January 2008, 10:31   #2
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I've seen a 4m yamboat SIB dislocating the whole transom plate while pulling a skiier. I suggest you have to check the specs of boat for max transom load.
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Old 11 January 2008, 13:05   #3
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Managed it behind a dory with a 25hp when I was younger, can't do it anymore.

I'd say you'd need a 40hp, to ski easily with adults. Definatly 2 stroke!!!!
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Old 12 January 2008, 11:59   #4
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Quote:
Originally Posted by samt View Post
Managed it behind a dory with a 25hp when I was younger, can't do it anymore.

I'd say you'd need a 40hp, to ski easily with adults. Definatly 2 stroke!!!!
The least i have wake-boarded of was a 10hp 3m rib and that pulled me up fine ( well it took a bit of time ), I regularly wake board behind my sib with a 15hp fs it will pull people up to about 14 stone after that it just gets too hard.. I think the key is the right prop and weight distribution especially in a sib.

James
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Old 12 January 2008, 12:26   #5
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The least i have wake-boarded of was a 10hp 3m rib and that pulled me up fine ( well it took a bit of time ), I regularly wake board behind my sib with a 15hp fs it will pull people up to about 14 stone after that it just gets too hard.. I think the key is the right prop and weight distribution especially in a sib.

James
That surprises me my 3.8 honda 20hp struggled with a donut if the rider was about 15 stone , that was with just one in the boat .
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Old 12 January 2008, 12:28   #6
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my 4m avon ski'd well with a 50 yom 2 stroke. it did struggle with my 16 stone mate but still did a reasonable job
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Old 12 January 2008, 13:35   #7
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my 4m avon ski'd well with a 50 yom 2 stroke. it did struggle with my 16 stone mate but still did a reasonable job
A 50 HP engine will be toooooo much, maybe have the transom dislocated, ideal will be to have 2 engines to test a 30 & 40 HP then let the buyer decide...

Happy Boating
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Old 12 January 2008, 13:56   #8
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That surprises me my 3.8 honda 20hp struggled with a donut if the rider was about 15 stone , that was with just one in the boat .
I have tried a donut and they seem to have far more resistance than skiing or wake-boarding when the rider gets up if the rider has the technique they will find it easy. Loads have my friends have said to me they find it much easier to get up behind my boat than a 75hp 5m rib because of the power they find it overwhelms them at first. A few people have tried to get up behind a more powerful rib and cant and they have tried on mine and found it easier because it all happens much slower then when they have tried behind the bigger rib they can get up.

James
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Old 12 January 2008, 14:09   #9
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I have tried a donut and they seem to have far more resistance than skiing or wake-boarding when the rider gets up if the rider has the technique they will find it easy. Loads have my friends have said to me they find it much easier to get up behind my boat than a 75hp 5m rib because of the power they find it overwhelms them at first. A few people have tried to get up behind a more powerful rib and cant and they have tried on mine and found it easier because it all happens much slower then when they have tried behind the bigger rib they can get up.

James

I hope to get some water ski's this year , haven't done it since I was 18
So are you saying that its better to pull beginers up very slowly and not try to get on the plane too quickly . My memory is the hardest time to balance is just as you pull out before the boat reaches the right speed , but it was years ago .
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Old 12 January 2008, 14:15   #10
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Quote:
Originally Posted by ian parkes View Post
I hope to get some water ski's this year , haven't done it since I was 18
So are you saying that its better to pull beginers up very slowly and not try to get on the plane too quickly . My memory is the hardest time to balance is just as you pull out before the boat reaches the right speed , but it was years ago .
Well it all depends on how much strength the person has but a two stroke just pushed to full throttle with tend to wrench the handle out of their hands. You need to apply the throttle so that the skis or board create some resistance and you can stabalise and balance yourself in the water then the power can be applied quickly and you will literally pop out the water. But every one has a preference and it much depends on the spotter and drivers skill to get some people up. I can be on the plane on a wakeboard when a rib is off the plane, obviously it is beneficial to have the rib on the plane but a person will plane slower than the rib.

James
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