What Idiot Approved this Design...

DrB · #1 (**permalink**) 09-24-2007

Motoring back to the mooring Saturday after a B-E-A-U-T-I-F-U-L sail out of Marblehead, MA, we encountered the first thing to break on our boat since we bought it. My wife normally helms the boat back to the mooring while I tie up the mainsail. During the tie up part, we motor slow to keep the apparent wind down and help keep the sail manageable while I reflake and tie it up. Once the sail is tied up, we increase speed until we get near the mooring.

So my wife hits the throttle on our Yanmar only to have the throttle lever, mounted on the pedestal, basically go limp. I tell her to drop the speed a little only to have her show me the lever now off the shaft and in her hand waving in the air, so no throttle control. We're going 6 knots in a crowded mooring field which isn't good, so I get a pair of channels locks, grip the throttle shaft and reduce the throttle to a crawl. 10 minutes and 200 yards later, we are on the mooring an I can survey the situation.

The throttle lever is a loose fit onto it's shaft. The only thing holding it on is a threaded 1/4" or so screw that threads through one side of the lever and into the throttle shaft. It does not thread through the other side of the lever, not even into it on the back side. Basically all the load of this lever, which is continuously, moved back and forth is on this screw in a small area in a shearing configuration. Threaded bolts/screws work best in tension than shear.

We sheared ours flush with the throttle shaft so that the bulk of the threaded portion is still in the shaft. I have to extract it some way so that I can put another screw in reattach the lever.

The current design is very poor. They should have a detent, notched or keyed fit to lever with the shaft and use the screw just to keep it from sliding off. Without the screw, the detent, notch or keyed surface should be more than sufficient for the forward back motion to use the throttle.

Gripe of the day, sorry.

DrB

sailingdog · #2 (**permalink**) 09-24-2007

They designed it so that it would be easy to assemble and cheap... operative word being CHEAP. If you want to make it better, you could always notch it yourself, and then get a new lever machined to fit... or modify the old one to fit. You'll need a good screw extractor to get it out. You can get a fairly decent one at Sears for under $20. Good luck.

zz4gta · #3 (**permalink**) 09-24-2007

Those "easy outs" are never easy. If you can't get it out that way, then drilling may be your only hope. After drilling, taping new, larger threads may be a better idea, or heli-coiling them would work as well. I'd upgrade that set screw either way. Any automotive machinist should be able to put a key and keyway into those parts. The machinist route won't be the cheapest one, but it won't ever fail on you again.

timebandit · #4 (**permalink**) 09-24-2007

Get a left handed drill bit, before you can drill it out it will screw out with the drill since there is no tension on the bolt. Mark the drill so you dont try to use it in the wrong direction.
Be sure to reverse your drill.

zz4gta · #5 (**permalink**) 09-24-2007

Quote:

Originally Posted by timebandit

Get a left handed drill bit, before you can drill it out it will screw out with the drill since there is no tension on the bolt. Mark the drill so you dont try to use it in the wrong direction.
Be sure to reverse your drill.

Yes, same thing an easy out does.

CapnHand · #6 (**permalink**) 09-24-2007

Be glad you weren't headed for the fuel dock.