Long Tail ..a question of balance

[pistnbroke]

I am putting together a long tail powered by a 6.5 hp Honda and my question is how do I deteriming the piviot point ...Logic would say point should be forward of the balance centre so the prop sinks but how much and am I right ??

[TerryKing]

I am putting together a long tail powered by a 6.5 hp Honda and my question is how do I deteriming the piviot point ...Logic would say point should be forward of the balance centre so the prop sinks but how much and am I right ??

Here are a few photos from Bangkok of LongTails I saw recently.. It certainly seems that the balance puts the prop into the water, the drivers hand is on top of the handle. The drivers seem to easily move the prop up and down.

Balancing a Turbocharged 6 cylinder diesel (the largest I saw) is not child's play!! These are amazing boats..

Small LongTail:
http://www.terryking.us/photoalbum/v/travel/bangkok08/P1010766.JPG.html

Pivot Points and drivers: 4 Cylinder diesels:
http://www.terryking.us/photoalbum/v/travel/bangkok08/?g2_page=11

A closer-up of the pivot. SEEMS adjustable!
http://www.terryking.us/photoalbum/v/travel/bangkok08/P1160548.JPG.html?g2_imageViewsIndex=1

Other weight-distribution example:
http://www.terryking.us/photoalbum/v/travel/bangkok08/P1160047.JPG.html

The whole album here:
http://www.terryking.us/photoalbum/v/travel/bangkok08/

I'd love to build one of these some time with an aluminum-block V8 :-)

HEY! Show us a photo of yours when you're done!

[pistnbroke]

Thanks for that Terry ....I deduce
Limit on downward movement of tailshaft even if it only hits the boat transom.
seem to retain gearbox and control of the lever ...anyone seen one go in reverse ??
Uses the clutch
the mounts would indicate slightly tail heavy but not much..

Well I have the centrifugal clutch and got the tail pipe/shaft and bearings yesterday . Have engineered the prop end with a taper roller bearing and oil seal so the job is moving...My shaft goes under the engine with a 2.11 chain drive so I can have a right hand prop ...

[TerryKing]

While we're at this: Can anyone ID this engine I recently saw used in small boats on Mabul Island off the East coast of Borneo?? They seem to work pretty well in these small (12 foot or so planing boats).

The Engine:
http://terryking.us/photoalbum/v/travel/borneo2009/boats/Borneo2009-Boats-34.JPG.html

A boat on plane:
http://terryking.us/photoalbum/v/travel/borneo2009/boats/Borneo2009-Boats-40.JPG.html

More boats:
http://terryking.us/photoalbum/v/travel/borneo2009/boats/?g2_page=7

The whole album:
http://terryking.us/photoalbum/v/travel/borneo2009/

(Click on any photo for larger; click again for even bigger)

These guys spend most of their time building, fixing and running boats, and fishing. I think I could live there!

[pistnbroke]

Looks like the 13 hp copy of the honda ..I think its Lupin or similar brand
I have the 6.5 hp version
dond see the point of extending the shaft so far behind the boat as you would only draw more water..better under the boat ...like the offset rudder

anyone out there built and balanced a longtail

[Mark Wo]

You certainly want to ensure that the longtail, when unattended, sits with the prop in the water. How much force is erquired to lift it out of the water is a personal preference. I've seen first hand what happens when the motor is balanced with the prop out of the water when unattended (my first mud motor build). I did not have a clutch on this motor either. Combination of the two was a horrible mistake.

I started the motor and pushed the boat off the shore. As I got into the boat, the motor swung around and the spinning prop almost hit me in the head. I've been told I have a hard head and all but I think the prop would hitting my head would have made short order out of me..

for what it is worth.

Mark

[Paraprop]

Hi,

I am living in Thailand and my hobby is to build long tail boats and tune Honda engines.

I would like to share the long tail setups presently available here.
The engine shown, is a new model of the 6.5hp engine from Honda with Digital ignition and "Marine" compatible parts. The governor is removed and the ignition has a limiter at 4500 RPM. the idle can go down to about 800 RPM with the special carb setup and the camshaft used.

the complete setup costs here about $400.- so no need to have headache with home R&D.

The equivalent setup with a 13hp engine is around $650.-