20''-25'' shaft

Discussion in 'Boats and Motors' started by stcroixjoe, Dec 26, 2008.

  1. stcroixjoe

    stcroixjoe (stcroixjoe)

    i have a 20'' shaft on my boat now could i put on a 25'' shaft on its the main motor what would happen?
  2. I am sure an expert will chime in and give the answer you need. I believe that if you put 5" of lower unit into the water that you donot need, I believe it would hamper performance. That being said, if you had a jackplate or if you raised the number of holes your motor is out of the water, it would reduce or even negate the loss of performance.

  3. I have run a 20" on a 15" transom before. There was enough power and performance, but there was a massive rooster tail behind the boat. This experiment was performed on a 16ft, bare bones boat with an Evinrude 35hp tiller. -Gabe :) Good luck, but I would stick with what you know when it comes to a big purchase like a main power unit for your boat! It probably wouldn't matter at all in the case of a kicker (longer shaft than necessary of course).
  4. Slow the boat down,spray water all over hell, cause a huge amount of torque steer, find plenty of underwater obstructions,and on and on....Without a jack plate to raise it to the proper height it will really suck.Been down that road with a 22" transom.Ran a 20" for a while and it cavitated and the hole shot was terrible.Went to a 25" and had even more of a mess. Added the jack plate and solved all my issues.