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Old 24 May 2017, 13:56   #1
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Country: Canada
Town: Calgary
Boat name: Mountaineer 360
Make: Salter
Length: 3m +
Engine: Mercury 20HP
Join Date: Mar 2017
Posts: 32
Too much weight upfront slowing me down?

So is there a fine balance in how to distribute weight in 3.6m SIB? My first trip out this year with the new 20hp mercury 4 stroke was with my father on choppy waters. We were able to hit 34kph together and 43kph on my own that day.. it took forever to get onto plane on my own because I have no weight up front.. the fuel tank was beside me at the back.

So to alleviate this, I extended my fuel line and mounted the fuel tank up front for the next trip. Last night I got out on completely calm water, was only able to hit 31kph with my friend with the fuel tank (1/2 full 25L tank) and a 15lb anchor at the front of the boat... we got onto plane very easily.

On my own, I was able to plane easily with this setup but I topped out at 35kph...

Does this mean I have too much weight up front? or perhaps its a trim setting? What should I try next? I have the trim set to 1 position from the lowest, I thought this was the right angle for it to be at..
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Old 24 May 2017, 17:01   #2
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Country: UK - England
Town: Sussex
Boat name: Bombard
Make: Aerotec 380
Length: 3m +
Engine: Mercury Mariner 15hp
Join Date: Jul 2010
Posts: 3,396
Yes, weight distribution in these lightweight, low power SIBs is very important. Trim for 90% of people is 2 or 3 holes out. Check Locozodiacs superb guide in the 'Which SIB' sticky for set up clues.

Many use a tiller extension as it's often better with driver midships. How are you sitting? On tubes or a seat - and where? With more weight in the boat a passenger may well have to lean up front to get on plane then retreat aft.
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Old 24 May 2017, 18:07   #3
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Country: UK - England
Town: Cambridgeshire
Boat name: Nimrod II
Make: Aerotec 380
Length: 3m +
Engine: Yam 15 Tohatsu 9.8
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Max is right weight distribution is very important but I am surprised half a tank of fuel and an anchor in the bow is reducing performance... that's assuming you are next to the tiller and not sitting amidships with a tiller extension??

However I just looked up your SIB and it is very heavy for a 3.6m at around 185lbs so perhaps it needs less balancing weight in the bow than those like Max and I have weighing around 95lbs which really benefit from some weight moved forward.

As Max says too movable weight (such as a light passenger) is often more helpful than fixed weight.

In the UK we usually think of speed in knots and on outing one your slowest equates to 18.5kts and fastest 23kts which is about the right range given the weight of your SIB.

I'd too say pull that trim position out another couple of positions to near a midpoint and see how the performance is then.
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Old 24 May 2017, 18:56   #4
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Country: UK - England
Town: Retford
Boat name: Spy-sea-one
Make: Excel 435
Length: 4m +
Engine: Suzuki Outboard/25/4
Join Date: Oct 2011
Posts: 7,441
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I have a 3.65 Mercury 43 lts of fuel two anchors, spares and a fibreglass bow dodger with all the electronics and battery in it 2-3 holes out 2 best for mine 22 knots with my prop 10 1/4 x 11 25 Suzuki four stroke I can sit anywhere at that
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