http://www.iboats.com/Transom-Elevators/dm/keywords.elevator--session_id.457648839--view_id.40157This type of thing is sold to those poor folk who have such old engones that cannot get the engine up due to not having
any adjustment holes in the engine bracket, and for those who want to use a outboard that has no holes, I.E smaller outboards of say 4/5/6 hp etc.
notice the amount of lift it puts the engine bracket up by is 1 3/4 inch and also a 2 inch model. !!!!!!!!!!
now these are not made to destroy your engine thrust and performance, they are designed for gains.
this is on normal transom heights.
the transom heights on outboard boats is normaly 15 inch for short shaft and 20 inch for longshaft.
during the later part of the 19080's extra long shafts became available for bigger boats with 25inch transoms.
and now we see xxl shaft boats with 30inch transom.
outboard engines from around 90hp onwards now come in 3 sizes, longshaft 20inch,xlongshaft = 25 inch, and xxlongshaft= 30inch.
The shortshaft engines have mainly died out apart from the under 25hp range you can still get them.
Now to explain the 20 inch transom outboard ..
the height of a engine transom length is measured from the bracket of the outboard engine to the anti-ventilation plate....not the prop.
the 20 inch (longshaft) is realy for boats that have a 20 inch transom.
BUT
the pic below shows a longshaft engine that is now used on a short shaft transom.The boat is 15 inch but the engine is a 20 inch.
YOU CANNOT JUST BOLT ON A LONGER H#SHAFT ENGINE AND EXPECT IT TO GO WELL.
the bracket now fitted is a raised setback.
the raise is 5 inch at the boat plus 2 inch at engine = 7 inch.
this is = to fitting 20 inch engine to 22inch trasom thus gaining a 2 inch lift.
THE ANTI-CAVITATION PLATE IS NOW 2 INCHES HIGHER THAN THE BOTTOM OF THE BOAT.
Speed gain ove 6mph over having it deeper in the water plus steering far more precise, fuel consumption less and no silly drag causing water to come back into the boat even at cruise speed.
Accelleration better as well so an all round improvement.
the bracket is not an home made bodge up, its a professional bracket costing around £200
also notice the steering tube is now 2 inches higher than original if fitted to longshaft transom
see pic below