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Old 07 April 2008, 13:22   #1
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Country: Austria
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Engines for Halmatic Arctic 28

Hello

thanks for the answers on my first posting!

The guys intrested in buying the Arctic 28 thought of using a pair of 150 hp Yamaha 4 stroke outboards they have left from an other boat.At least until they buy a pair of 225 hp outboards

I know thats not much for this RIB and my question is: Will these motors plane the boat and which speed could one expect?
Would it be helpful to install planing chines or special props?

Thanks a lot and best greetings,

Thomas.
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Old 07 April 2008, 14:55   #2
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Country: UK - Wales
Town: Southampton
Boat name: DynaMoHumm/ SRV/deja
Make: Avon8.4, 5.4 & 4.777
Length: 8m +
Engine: Cat3126 Yam 90 &70
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it'll plane OK Dunno about top speed depends on payload but you'd see 25 knots. You'll also a fairly high fuel consumption cos these engines will be running very hard

The Artic if I recall has a very large planing Pad and this could with fairly heavy lowish powered lumps on the backmight make the boat bow happy. So I would be looking at forward weight distribution and trim tabs.

it'd lovely with a pair of Big Happymax's clipped on the back
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Old 07 April 2008, 14:59   #3
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Country: UK - Channel Islands
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Boat name: Martini II
Make: Arctic 28/FC470
Length: 8m +
Engine: twin 225Opti/50hp 2t
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Hi Thomas
Sorry I haven't replied to your pm yet, very busy at the moment!

I think a pair of 150hp's should push the boat along ok, you shouldn't have much problem getting on the plane. They're heavy boats but not that heavy!

I'm not an expert on Yamaha props but a pair which are designed to give more lift at the stern rather than a racing prop certainly would help.

I would guess 30-35 knots, maybe slightly less when you are carrying 10 people and also depends on the size and weight of the cabin you were talking about.

Matt
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Old 07 April 2008, 16:30   #4
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Country: UK - Wales
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Boat name: DynaMoHumm/ SRV/deja
Make: Avon8.4, 5.4 & 4.777
Length: 8m +
Engine: Cat3126 Yam 90 &70
MMSI: 42
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Quote:
Originally Posted by martini View Post
Hi Thomas

I would guess 30-35 knots, maybe slightly less when you are carrying 10 people and also depends on the size and weight of the cabin you were talking about.

Matt
I think that's a bit on kind side

Your lumps have 50% more power to weight ratiocan Iask what your WOT speed.

Also the cabin's gonna act as a windbrake 10 people are gonna weigh 600 kilos 300 litres of fuel safety kit weight of the cabin there's an easy tonne ( note the ease I switched into Metric measurement there for our Eurobuddy )

There is another issue when you are driving a laden passenger boat with marginal power namely the engines don't have the snap to properly power off the waves so you sometimes wind up going on and off the plane in bigger seas (not a lot of fun) and 4 strokes don't have the initial snap that 2 strokes have a struggling 4 stroke is gonna deliver power more slowly.

One other point the Artic's don't have transoms which makes it a feet wet boat, make sure your deck and glands are absolutely watertight and you have good redundancy on your bilging system cos you don't need to carry any excess weight with bilge ingress

anyway I'm off back to sea for a month so you guys will have to sort it out without me. have fun
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Old 07 April 2008, 16:59   #5
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Country: UK - Channel Islands
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I didn't realize 4 strokes were so much heavier, glad I didnt take that route!

I was being quite opti-mistic there actually
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Old 07 April 2008, 18:35   #6
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Country: UK - Wales
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Boat name: DynaMoHumm/ SRV/deja
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I didn't realize 4 strokes were so much heavier, glad I didnt take that route!

I was being quite opti-mistic there actually
like it! the opti's are actually 11 kilos heavier or 5% ish
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