Outboard Offsets

[Markyboyo]

What exactly is the purpose? Is this simply to counter poorly distributed weight in the boat or to counter handling tendancys caused by the propellors rotation?

Mark

[matt h]

to counteract the Prop torque! some more than others, the craft manufacturer will advise the offset if any!!

[Markyboyo]

Thanks for that Matt, makes sense. I'll have to get on to Humber before I have the Etec fitted up...unless anyone can advise on a 5.5 destroyer??!!

[matt h]

three quarters to one inch to the right, looking from behind, using a recommended engine within limits, eg weight and power, would be about right, a few millimeters either way is not going to make any difference,

[BruceB]

You will struggle to get more than about an inch depending on the engine width and transom height on a destroyer. I got exactly one inch which was the maximum I could have got without resorting to a saw in the transom cutout.
Its all a compromise, my outboard is slightly offset to stardboard but the fuel tank is offset to port and when I am driving the boat alone I sit to starboard, god knows what direction the boat will end up listing to

[Markyboyo]

I think my transom is prob rather different to yours Bruce, what with the aux cut out and being for an XL transom. It dosen't have the raised splash plates like yours, I'd post a photo but the boat is 4000 miles away!

[BogMonster]

Is there a formula for calculating offset based on HP/hull length/phase of the moon or is it just a trial and error thing and the manufacturer will determine the best setup?

Just wondered as I know of a boat here which is awful (not a RIB) under full power it feels like it is going to sink with probably 15-20 deg of bank to port!

[Cookee]

Originally Posted by BogMonster

Is there a formula for calculating offset based on HP/hull length/phase of the moon or is it just a trial and error thing and the manufacturer will determine the best setup?

Just wondered as I know of a boat here which is awful (not a RIB) under full power it feels like it is going to sink with probably 15-20 deg of bank to port!

There is no formula as every hull behaves differently - We put every engine in the middle and with careful prop selection and engine height adjustment we have never had a problem - trimming in too much also can accentuate any problem!

[BruceB]

Mark,
I thought yours was XL as well but with a cut out on the port side for an aux?
Mine doesn't have raised anything AFAIK, just made for an XL shaft motor.
Does that mean your transom is different if both are supposed to be XL?

[Hightower]

Originally Posted by matt h

three quarters to one inch to the right, looking from behind, using a recommended engine within limits, eg weight and power, would be about right, a few millimeters either way is not going to make any difference,

Not all of us have one that hangs from the right