Difference in weight between Inboard and Outboard IF boats

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OGB
Inlägg: 12
Blev medlem: ons 22 jul 2009 16:19
Ort: Cornwall

Difference in weight between Inboard and Outboard IF boats

Inlägg av OGB »

I am interested in the weight of my IF boat. Reg no 2630. What is the difference in overall weight of one fitted with an inboard engine and one without? I had a volvo MD1B probably fitted as original equipment in 1976 when boat was built by Marieholms Bruk. The basic information given is
Model Number LOA LWL Beam Disp Ballast
IF Boat 7.87m 6.05 m 2.20 m 8.75 kg / 2.15 ton 5.09 kg / 1.25 ton
LOA = Length Overall = Längd överallt
LWL= Length at Waterline = Längd i vattenlinjen
Beam = Width = Bredd
Displ = Displacement = Deplacement
Ballast = Weight of Ballast = Långköl

Having taken the MD1B out (weight 165 kilos) and replaced it with Dolphin Series 2 (weight 54 kilos) the boat now is down by the bow which makes me think that compensatory ballast was installed in the bow. Is this in addition to normal ballast or was the distribution of ballast changed ? How was this achieved Is the ballast in the form of "punchings" mixed with fibre glass in the build process or were there one or more solid weights fitted as an afterthought which could be easily removed/relocated.

OGB
Inlägg: 12
Blev medlem: ons 22 jul 2009 16:19
Ort: Cornwall

Re: Difference in weight between Inboard and Outboard IF boa

Inlägg av OGB »

Posted by Thorbjørn, DEN 312

Are you sure that it is down by the bow? I mean, of course it is if you compare with your usual waterline but what if you compare with the drawing? You have perhaps already done this comparison ..

My answer

Yes the boat is down by the bow to the extent that the cockpit drains into the bilge rather than through the aft cockpit drains. Obviously the position is better with two heavy crew aboard.

Nils D
Inlägg: 180
Blev medlem: mån 04 jun 2007 19:21
Ort: Linköping/Arkösund
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Re: Difference in weight between Inboard and Outboard IF boa

Inlägg av Nils D »

As far as I know, it was actually the other way around, i.e. the weight of the keel was reduced on the IF:s equipped with an inboard (also called IF-E) to compensate for the weight of the inboard engine. I tried to check oround a bit on the Swedish forum, and as far as I can ascertain the keel was reduced by 150 kg in its aft part. Which I guess means that to compensate for the reduced weight of the new engine you should add some compensatory ballast to compensate for the smaller engine you have installed.
Nils D SWE-3008

OGB
Inlägg: 12
Blev medlem: ons 22 jul 2009 16:19
Ort: Cornwall

Re: Difference in weight between Inboard and Outboard IF boa

Inlägg av OGB »

Many thanks Nils, I am going to do as you suggest . I am gathering some lead to melt down.

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