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PostPosted: Mon Aug 18, 2014 6:27 pm 
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Site Rank - Deck Hand

Joined: Thu Jul 31, 2014 7:38 pm
Posts: 11
Location: Jacksonville, FL
After taking forever to get through a draw bridge in the early afternoon then smacking a poorly maintained dock, I thought about a simple trolling motor on the 16. Here is what I have in mind.

I'm looking at the following trolling motor set-up for a Hobie 16
1. Machining a a derlin block which adapts a tiller motor shaft to the Hobie 16 crossbar
2. Gutting a trolling motor or just buying repair parts for motor, prop and shaft
3. Trimming shaft to appropriate height installing a permanent stop
4. Epoxy keyway to shaft to prevent motor from turning
5. Install an adjustable locking collar which allows motor to raise up and down
6. Install one or two Shorai LiFePO4 batteries in a floating neoprene/foam bag with speed control and waterproof plug to motor head

The Shorai batteries are designed as starting batteries, however the chemistry should work well in a deep cycle application. I'm just unsure as to the charge control circuitry in the battery. I sell these batteries and can save a few bucks testing one for this application. The motor with prop and shaft from a trolling motor is affordable, especially how higher range product.

I'll document my progress and share results, but have the following needs:
1. Anyone use an electric trolling motor on a Hobie 16? Models? Results? Published thrust numbers?
2. Anyone use a fixed motor while retaining rudder steerage?
3. Anyone with expertise and ability to make the block rotate so the motor shaft need not protrude when not in use?

Post if you are interested in such a project.


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PostPosted: Wed Oct 08, 2014 12:45 pm 
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Site Rank - Deck Hand

Joined: Sun Feb 23, 2014 8:54 pm
Posts: 5
I cant really speak to the 16.

I Had been running my Quest using a 30 pound thrust motor since 2008.

Everything was connected to the kayak via quick release pins. No bolts were used and could be converted back to a paddle kayak in less than 30 second.

You'd be surprised how well the factory rudder bracket and rear plastic held up for the amount of abuse I put it through.

I did install a carbon plate between the bracket and plastic to prevent flex fatigue. Worked excellent.

The controls were mounted on the hatch near the seat. Steering was with the rudder peddles. Was truly hands free fishing. Have since sold it.

Everything you mentioned has been done to the motor below. Feel free to ask questions.

Image


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PostPosted: Thu Oct 09, 2014 6:01 am 
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Site Rank - Old Salt

Joined: Sun Apr 20, 2008 6:18 am
Posts: 1373
Location: Sarasota,Key West FL
I helped a guy a while back designing a motor mount for an h16, I have no idea if he ever made it but the concept is very simple and easily removed from the boat (for racing) and doesn't require any mods of any kind to the boat itself, or require any machining of any kind.
Basically what you need is 3 pieces of pressure treated 2x4, an off the shelf 30# trolling motor (about $90 bucks at Walmart) and some spectra rudder line like they use on the rudders on Hobie kayaks (available at any Hobie dealer for about $.30 cents a foot ( it's the grey 700 lb test no stretch spectra string).
Most transom mounted trolling motors already have the tilt up capability and a slide up and down sleeve with a thumb screw to lock the motor to a certain height and the ability to lock the tiller straight, might as well use them (their free and come with the motor). You would cut 1 2x4 to about 10-12 inches long (this is the transom board and you cut to fit the motor, next you cut the 2 other 2x4's to about 8 inches long (again length is custom to your motor, and make sure it can tilt up and lock easily). One end is screwed and glued to the transom board to make a U shaped structure. Next you cut 45 degree grooves onto the 2 ends so it fits nicely onto the cross bar. Next you get some 1 inch strapping material and toggle clamps (like cargo straps (really cheap at Home Depot)) and strap the tiller board assembly to the rear crossbar.
Now next you need to drill and tap a couple 1/4-20 holes into your rear rudder transom boards on the h16. Then put in two stainless eye bolts into the rear of the boat ( one on each hull as close to the inside as possible, as high as possible), (this is the only actual mod to the boat itself).
Now run two pieces of spectra string from the back outside corner of the motor mount (adding a small screw in eye bolt into the transom board (one in each corner) gives you a good place to tie the strings. At the eye bolts at the back two removable D clips are snapped onto the eye bolts then the string is pulled tight and knotted (cinch knots work best). This forms a truss structure, now you place the motor onto the transom board, obviously you want to adjust the strings and motor tilt so the motor points straight down with everything taught. Next you run two more spectra strings from down near the bottom of the shaft back to your eye bolts in the back via d clips (these two strings are what take all the forward torq and force from the motor propulsion so they are important.
When the motor is tilted up these two strings just become slack.
I've had a similar setup on my tandem island with twin honda 2.3 outboards for a long time now with no issues ( that spectra string is 700 lb test with zero stretch, and lasts forever (I've been using the same piece of spectra string for 4 1/2 years now, and I'm out there using it every weekend).
The coolest thing about this setup is it is completely removable in about 30 seconds leaving nothing on the boat itself (for racing). To install you just cinch two straps at the cross bar, and clip 4 clips back at your transom and your good to go, I have never had to adjust my strings ever, just clip them on.
To use the motor you just tilt it down and turn it on, with the thumb screw tightened on the shaft it always points forward and you steer with your main rudders.
The best part about this setup is if you need to maneuver around a dock area you can raise your main rudders and drive around any direction with the motor (like an isopod), you can drive sideways or backwards just by unlocking the thumbscrew and turning the motor.
Sure you can go out and spend big bucks on a cheeta motor mount (I think they are $300-$400 buck) and mount it permanently to the boat if you want, but this mount is stronger and only costs about ten bucks to make and an hour or two of your time.
Ps it would also be perfectly suitable for a small gas outboard also (that's what I have (actually twin outboards to be exact because I'm far offshore a lot).
Hope his helps
Bob
Edit:
The trick to this setup is when the transom board is pulled tight by the 2 first spectra strings it will be tilted down slightly, you may need to do angled cuts on the ends of the short boards so the transom board points straight up and down with the motor mounted. You may need to adjust the distance to the water to suit your particular motor. Once completed you should be able to mount any brand standard transom type motor onto the mount if you want to try different types.

Disclaimer:
I don't own a cat and have never been on one, the above design is what I thought thru and discribed to a guy on this forum who was trying to do the same on his H16 as you about 3-4 yrs ago. Of course you will need to work out your final heights yourself but the concept remains the same, and should be able to be applied to any cat, however I am an engineer and know how to design things ( I do this for a living). Basically if I did have an h16 and wanted to mount my honda or a trolling motor, this is how I would go about it (that's all).


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