surface drive?

[foamlover]

What is the diference between surface & submerged drive? Besides the obvious. Wouldn't it be bad to have prop to near to the surface? :confused:

[foamlover]

Sorry if this is an obvious question. I am jut a lowly noob. :rolleyes:
Any response would be appreciated!

[Kmot]

Don't apologize for the questions. It's okay. We all had to start somewhere! ;)

A submerged drive, means just that. The prop is submerged under the water 100% of the time. Examples of this are scale boats, that have a prop shaft angled through the bottom of the hull and the prop about 3/4 of the way toward the rear of the boat but completely under the hull.

Surface drive is usually with an outdrive bolted to a strut. The prop has one blade in the water when turning and the other blade out of the water. These are for speed boats. One blade in the water has less drag then two blades in the water. One blade being driven through the water takes less power than two blades being driven through the water.

You normally won't see a surface drive system on a scale type boat. You will normally see them on fast electric race boats and fast nitro boats with hulls designed for the purpose of racing and not necessarily following any actual scale boat designs.

[Shaun Hendricks]

Modern turbine hydrofoils use surface piercing drives. There are many others that do this as well. The US Navy is working on ships that will use surface piercing drives in order to maximize speed and efficiency. These will likely be fast boats that aren't sub hunters.

The efficiencies of surface piercing drives are very tempting to many nautical engineers, but making them effective over a wide range of hull types has proven elusive. That's the short version of a few 'university type' articles I've read on them.

[foamlover]

Aahhhh, I guess that explains all those lovely rooster tails you always see behind the fast boats. It sounds like the submerged drive is a heck of a lot easier to set up, is it worth the effort if you are not going for just all out speed? Can submerged drives also be reasonably fast? Maybe it would be worth any extra work just to see those wonderful rooster tails :D ! Man I love hydros!

BTW, do submerged drives get better manueverability? Or power without speed? What are the other advantages and disadvantages of each?