steering torque help

tkp333fl · 22 June 2007, 07:00

What do they sell to help with the steering torque on a zapcat? And where can I purchase?

prairie tuber · 22 June 2007, 08:08

The sacrificial anode on the underside of the antiventilation plate has a small fin. On my 25 hp Mercury 'classic' (built by Tohatsu) it is aligned directly inline with the skeg, but on my 40 hp Yamaha, it is offset to minimize steering torque. Check and see if you can adjust the angle of that fin.

prairie tuber · 22 June 2007, 08:10

By the way, welcome to ribnet! What all did you do with your Merc to uprate it from 40hp to 50 hp?

Jono · 22 June 2007, 08:17

Quote:

Originally Posted by tkp333fl

What do they sell to help with the steering torque on a zapcat? And where can I purchase?

May I recommend a "Charles Atlas" course...?

Cookee · 22 June 2007, 13:47

Bungee cord!!!!

tkp333fl · 23 June 2007, 11:39

Thank you for the info.

The Mercury 40hp 3 cylinder Classic is the same as a 50hp motor, but with smaller carb's and reed valves. I just changed them (couldn't find a short shaft 50hp so I went in this direction).

As for the sacrificial anode. I tried it all the way over and even had the machinist at work cut a few extra notches in it (originally only 25 deg left or right, I maybe added an extra 5 deg). I have the motor set pretty high to try and keep up with the jet skis when we go out. 40hp only 47 mph gps, 17 pitch prop raked and cupped, 3 blade. Have not gps the 50 hp, but want to go to a 21 pitch semi clever prop). It’s slow getting on plane (I gun it, slow down, let the water build up behind it and then I can take off). Anyway, the torque tab doesn't do much, but helps a little.

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As for the Charles Atlas course. I need too. I put a 10 galloon and a 6 galloon tank in the boat so I can get 4 hrs of wide open drive time. My arm starts too burnt out (note, I try to keep my arm strait and lean to offset the torque).

I was thinking about adding a hydraulic steering cylinder with a hand lever valve on the tiller, and then when I want to turn, pull the lever, turn, and then release. It would then lock the motor in place.
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How are the bungee cords set up? a photo would be great?

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Thanks again.

prairie tuber · 23 June 2007, 14:17

Quote:

Originally Posted by tkp333fl

Thank you for the info.

The Mercury 40hp 3 cylinder Classic is the same as a 50hp motor, but with smaller carb's and reed valves. I just changed them (couldn't find a short shaft 50hp so I went in this direction).

No need for exhaust port modifications? How do you like the DUX? Have you got some pictures of your setup?

Thanks

tkp333fl · 23 June 2007, 22:12

No exhaust port modification,,,, so far,,,, I talked to mercury help line and the mechanic at the local dealer. Nothing came up as different except the carbs and valves. So that is what I got. I will look back into it, I may have missed something? (note: I know enough just to get me into trouble, but not enough to do the job correctly)

I don't like the dux. I have had really bad experiences with it and the company. They seam like they want to help and mean well, and it may just be this one case, but for me it wasn't a good thing. I wanted to get into the sport, but didn't want to spend much (and be able to get out if I didn't like it). I regret not going with a top line manufacture like zap cat, Aquarius, or Caesar. But they are hard to find and twice the cost.

As for the setup, its just a normal setup. I am looking at something for the steering torque. I did find a company that makes power tiller steering, but it is for larger motors. It has a small hydraulic pump and the twist throttle has a little left right movement that operates valves to operate the left right power tiller steering. The company is out of Wisconsin, but I think 70 hp is the smallest that they make it for. I was looking into it, but I didn't have enough amps off of the motor and I started looking at a battery, but decided the extra weight of the pump and battery wasn't what I wanted. I also looked at making my own, but couldn't find a low volume steering cylinder and a hydraulic motor that could do the job in the amount of time I wanted (full left to full right in around 1 sec). I didn't put a lot of time into it and may look back into it?

Thank you

prairie tuber · 24 June 2007, 02:36

I'm not sure if mods to the exhaust port would be of significant benefit for your motor, although I know it is often done when an engine is uprated via a carb/reed valve swap. Fast Fred from the board here is a real guru for this sort of stuff.

Thanks for the info on the DUX. I had considered getting one last summer because the price was attractive, but ended up going a different route on the advice of a board member here who's had lots of experience with tunnel hulls (and bears a remarkable resemblance to the previously mentioned board member

).

The hydraulic pump seems like alot of weight, clutter & power sappage. Have you tried offsetting the motor slightly from the center of the transom?

tkp333fl · 25 June 2007, 00:31

Yes, I have read some of Fast Fred's posts and he seems like the man.

Thanks for the info. Searching I found "the engine should be offset slightly to the Starboard by 1" per 100 hp." I will give that a try.

Thank you so much!

Have a great day!

prairie tuber · 25 June 2007, 07:02

Please let me know how it goes. BTW, do you have a link to the site where you found the engine offset formula?

Cookee · 25 June 2007, 11:53

Quote:

Originally Posted by tkp333fl

Thank you for the info.

I was thinking about adding a hydraulic steering cylinder with a hand lever valve on the tiller, and then when I want to turn, pull the lever, turn, and then release. It would then lock the motor in place.
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How are the bungee cords set up? a photo would be great?

-------------------------------
Thanks again.

The Thundercats have a hydrualic damping system with a valve which helps with the snatch as the boat re-enters the water - the bungee is tied from the tiller to the safety line on the tube to counteract the pull when going in a straight line - I would get in touch with Thundercats and ask if they will supply you with a damper - http://www.thundercatracing.co.uk/

tkp333fl · 27 June 2007, 02:17

I will be out of town for a while, but when I try it I will let you know if/how it works.

I found the post on this forum.

pete7 posted:
Nugent, the engine should be offset slightly to the Starboard by 1" per 100 hp so 1.35 max for you to counter the touque from the single prop which will tend to make the boat run on one side if the engine is central and the LWL short in comparison to the beam and draft. On a long LWL you can get away with a centre position. We recently moved my offset engine back onto the centre line (Ribtec 6.5m) and the handling is better.

http://rib.net/forum/showthread.php?...teering+offset

I will also try a bungee and look into a damping system.

thanks you for all the help.