Surface Drive Info

I have done some searches online but have come up with nothing. Anyone have any suggestions? I could use some technical drawings, principles etc. The big commercial drives are out of the question.

Thanks,

Joe

 

What's the application - there are any number of surface drive manufacturers - try searching for Q-spd, Arneson, Seafury just to name a few, or go to the design.net directory http://boatdesign.net/directory/Propulsion/Drives/

 

Surface drive tech paper

www.well.com/user/pk

 

What is the intended application and HP?

 

Are you sitting down?

The intended application is a real world pupulsion system for a 15-17 ply, multichined skiff. Gross weight 1000 lbs max, beam, oh say 6'. Power plant issssssss a lawnmower engine. Horizontal shaft. 27 HP/3500 RPM. Easily adaped. Air cooled. HP may be a problem, I might have to go with twins. Or da farfegnugen. (VW) But damn I am having a hard time finding them.

Thats it. I am not crazy. I have the basic design in cad using aluminum heavy wall tubing, u-joints, pillow blocks and thrust bearings. It still has issues but I think it just might work. The whole thing looks sort of like a upside down skewed radio tower from HBO's new series Carinval.

Thanks,

Joe

 

I think it's OK. However, you'll have to find a propeller designer and someone to manufacture it. It should run $3-4K for one done at a reputable propeller machine shop. Also, lawnmower engines produce very little HP for their weight. They are designed to run at a constant RPM and have little torque at low RPM. It may be possible to do major modifications and make it work, but it will end up costing more than an engine made for the application. Multichined skiffs are for sailing/rowing. The idea is to have a narrow waterline with reserve floatation up. It is the opposite of what you need for a planing hull with very low HP as you are talking about. Maybe a flat bottom boat may get up on plane with 27HP.

 

Adaptation of land engines

There are a number of adaptations required for non-marine gasoline (petrol) engines to render them safe for marine use. Contact the local Caost Guard boating safety office.

 

Ouch!

Three grand for a prop?! That's a issue I can't over come. If I can't find a reasonalbly suitable stock prop then it can't be done. (I understand the difficulty here. Normal props are not designed to work as surface drive props.)

Regarding the mulitchine... It is basically a flat bottom boat with a slight V aft but with most of it's V forward to reduce pounding. The flatness of the bottom aft also makes for a simpler to build, easier to work from craft. Plus, the only place in Fl that you can use a flat bottom boat is inland on a farm pond. Otherwise your fillings get shaken out.

Thanks for the word about conversions of engines to marine applications. I will be sure to contact their web site for that info. If you have a URL I would appreciate it.

Regards,

Joe

 

I am working on a design for surface drives. A 36" prop is $22,000.00 . The problem with your application, is that it's not standard. However, with surface props, to make them efficient have to be matched to the boat and installation.

 

Surface Drive Outboard

JOE,
I HAVE BEEN READING SOME OF YOUR MESSAGES. I CAN TELL YOU THAT
I HAVE KNOWLEDGE OF YOUR VERY SUBJECT ABOUT POWERING THE SKIFF
WITH THE AIR COOLED ENGINE WITH A SURFACE DRIVE. I HAVE BEEN DEVELOPING A SURFACE DRIVE OUTBOARD WITH AN AIR COOLED ENGINE
AND IT DOES WORK. I CURRENTLY HAVE A 10 H.P. PROTOTYPE THAT I
HAVE BEEN TESTING FOR OVER A YEAR. THE 27 H.P. KAWASAKI I PRESUME
IS AN EXCELLENT ENGINE. I WOULD SAY IT WOULD POWER YOUR 1000lb
FLATBOTTOM SKIFF FINE. YOU WONT TAKE IT TO THE RACES BUT IF
YOU ARE LOOKING FOR SHALLOW WATER RUNNING IT WILL WORK. I CANT
FIGURE OUT THIS FORUM TO WELL BUT IF YOU GET THIS SEND ME
AN EMAIL DIRECT dragons002@yahoo.com

 

Levi Drives

We have developed a suface drive for fisherman with hand steering. The smaller version Levi Drive 170 - 125 would be suitable for your application.
Visist our webpage www.levidrives.com.
We have a set of props for these drives 17" and 5 different pitches CW,CCW. The price is about 250 $ US.

Cheers Capt Rudi

 

prop price

Hey Gonso
Where do you buy your props from ? that seems very expensive.
Is that in US $ , we would sell that size for a lot less.
Greg

 

Totally doable....

I got a small racing boat using a home-made surface drive. Works awesome. Could slap it into your skiff easy.

Lawnmower engine power to weight? Suzuki DT-8 2 stroke 8 HP O/B weighs 73.5 LBS, Honda GX-240 weighs 54 LBS,makes 7.9 HP. Granted, my DT-8 powerband is more suited to turning most of the props I have tried, but I'm getting really close....

Now, My current race boat uses a Honda GX-270 , 8.5 HP , weight is less than 50 LBS owing to the use of performance parts readily available for these "lawnmower" engines. I can achieve 7000 RPM+ on pump gas, and 25 HP easy if I want to.

Just build one. It's a hoot.