stinger drive length

[RIPFENCE]

hi all,

stinger drives come in various lengths...what would be the advantage/disadvantage of running a longer drive instead of a shorter one..would you have more lift with a longer drive? would you need more or less positive trim angle to create lift with a longer drive?? maybe these questions are a bit elementary but i am unsure how different lengths effect handling..

[m4a1usr]

Think of the stinger length as a lever arm as related to force location. There are benefits to a long stinger. Like putting the prop behind your rudder if you have a narrow transom. Greater bearing surface. But there are also disadvantages to a longer stinger. It can effect the steering and stability. Just look at real boats for examples. Its tough to find a 40 foot,100mph offshore boat with a prop located 4 feet behind the transom unless they are using outboards.

http://www.exrx.net/Kinesiology/Levers.html


John

[RIPFENCE]

jon thank you for the info..the lever diagram you found was hilarious but informative...it reminds me of the stop drop and roll pics that we all saw in third grade as well as the hide under the desk when an earthquake happens diagram...it does make sense to me now...i guess thats why real boats would have standoff boxes on the out drives

[CornelP]

As far as I've seen on different web pages, the normal length is 10-13% of boat length. I did try with a longer one, but, as John was saying, steering was a bit stiff. And this was 20mm on a 70mm stinger. One guy at our pond has a very short stinger on an ancient Graupner Mega Dragstar 1 (30mm on a 600mm boat): works ok, but if you go heavy on the steering, it will just spin...

[Simon.O.]

I had a good look around at the big C1 boats from Europe and I see most that have the prop close to the rear of the overhang and that would give them about 10% aft of the true(wet) transom.
I estimated my dimensions based on proportions of 40-42' (common C1 hull lenghth)

I have 3 cats that all have the prop well aft of 10%.


I will admit that I am very biased towards Cats and know less about monos.
I tried a fast mono once and it was not for me.

[ED66677]

I had the chance to make one too long on my first boat, about 16% hull lengh, it simply provides a "better" hull lengthwise stability, the bow doesn't bounce much then, at this time I felt it was more difficult to adjust prop angle, for the same angular deviation, a longer stinger brings the prop much deeper than a shorter one, just few thing that I noticed, I now blindly use the 10% rule!