Shafts thru the transom?

[Frosty]

What exactly do you do Tom? Do you design or just experiment with like, surface props and rudders n stuff.

[tom kane]

Thanks for the comments jackfrost,we do have to work with compromises and engineering practicality.Propeller HP requirements can be controlled by propeller diameter,pitch,blade area,boss size and blade thickness and number of blades in S/P propellers and also by masking and or ventilating the top half of a S/P propeller and depth of immersion in water(hydrostatic head) and also using a kort nozzle or shroud which may allow the use of a smaller prop and shafting.Older fast boats which had a steep shaft angle and props operating in S/P mode ( propriding on the boss) lifted the back of the boat very high and lost contact with the water,and had a long way to drop.I have done a lot of experementing with propulsion but take a big interest in what others do and use and what works well,and not afraid to loose a few knots for something that does a good job.Working in a small scale is easier and much cheaper and quick to make and alter,the results can be scaled up.

[Frosty]

Do you mean you do all this experimentation stuff on models

[tom kane]

No the basic research is carried out by Glogal Research to collect data published by the many papers published in all fields.There is no point in going over work already done.New concepts are checked for patentability or design interlectual property claims.there is little point in using patented ideas for production.trials are made on the boats on all sizes you see in my photo album.Computer software is used to check where ever possible.If propulsion is used in the field and especially for racing,trials are already being done,so no need to spend time and money in a pointless exercise.

[Janamon]

Hi all check out Seafury International. They are producing quality stuff now days. Very simple installation, low maintenance. Getting some very good and fast results.

[Janamon]

Hi all check out Seafury International. They are producing quality stuff now days. Very simple installation, low maintenance. Getting some very good and fast results. Check them out at www.seafury.com

[stonebreaker]

How would you go about calculating the difference in speed a surface drive would make?

I assume if you had a boat with a known amount of engine power/propeller thrust, you could calculate the overall drag at top speed. Then you would calculate the drag for the propeller shaft, subtract it from the overall drag, and then recalculate for top speed.

How do I go about doing that that? I'm a computer geek, never even took calculus in college, but if someone could give me the formulas so I could plug in the numbers or even point me towards an online calculator I sure would appreciate it.

[RANCHI OTTO]

http://www.well.com/user/pk/SPApower.html

[gofastgeaoge]

New to the group but am glad to find this site. Question is could you use a normal rudder for steering with an arneson surface drive? Or do you have to have to have the surface drive for steering?

[Steve H]

Many people have done this. Use the rudder for steering only and keep the trim function of the arneson. Or forget the trim, just replace the trim rams with a solid rod.

Steve

[Frosty]

Where will you mount the rudder? On the boat itself. If you gone to all the trouble to make the shaft steerable it is therefore trimable. Why go through all that work and not trim it. Its just a ram.

[Steve H]

Originally Posted by Frosty

Where will you mount the rudder? On the boat itself. If you gone to all the trouble to make the shaft steerable it is therefore trimable. Why go through all that work and not trim it. Its just a ram.

You are asking questions that most people would. gofastgeoage had a question and I answered it. I have seen the set up on many high end boats.

[Pericles]

How about a surface piercing drive that does not need a rudder, nor adjustment for trim? A drive that also delivers the ability to walk the vessel sideways for docking using joystick control and without a bowthruster. A drive that is so efficient that smaller engines can be fitted in a hull that would otherwise require more power when fitted with conventional shafts.. It exists.

See the videos. http://www.yellowfin.com/VSDTechnology.asp

Pericles

[Frosty]

Pericles --have you seen the Yellow fin system it really good you would like it. A lot