The resonance has become a little less and occurs at somewhat higher RPMs as well.
BHPian Jeroen recently shared this with other enthusiasts:
No solution on the converter yet! Alex was going to borrow a frequency/spectrum analyser from a friend. But the friend has switched jobs, so he no longer has access to the analyser.
I have had good support from the guys from the latest one. They actually proposed visiting Sirion and doing some onboard troubleshooting. Excellent service. We still need to set a date.
Yesterday I spent more than 6 hours on Sirion trying to fix another little, but very annoying, problem. When throttling up over 2000 RPM, the throttle handle begins to resonate. I investigated, and it appears it comes directly from the engine, through the two so-called Morse cables. (one for the throttle, one for the clutch).
I did some further digging into this phenomena. The throttle is made by Morse, lots of boats have a Morse throttle handle. One handle that controls the clutch and RPM.
The cables are a bit like Bowden cables as you would find on some cruise controls on cars. It can push and pull. Which also means it has quite a sturdy inside cable and outer casing. Because it is all pretty sturdy and inflexible, it actually makes the throttle handle vibrate. Luckily, I found somebody who makes a Morse cable damper set. I ordered two and set off as soon as they arrived.
Only to be met with two Drammers!!
You will have seen this second Drammer earlier on in this thread. It belongs to a very nice older gentleman, who has it since new. Every year around this time he locks up his house and spends the next 4 months sailing all across the Netherlands.
So we had a bit of a chat.
Onto the job at hand. The kit is fairly easy. In essence, a rubber enclosure that goes around the cable and isolates it from the engine mount.
But it wasn’t that easy to install, or rather it was a pain removing the cables.
This is the clutch slide assembly.
This is the throttle (rpm) slide assembly
Part of the problem or why it is a bit more complex on Sirion, is I have two throttles, thus four cables. Remember I have a throttle in the open cockpit so you can steer in the open air.
Eventually,
I managed to take the clutch assembly apart.
Put the end of the clutch cable into the rubber enclosure bits. Looking good I thought! It goes into a bracket, and I had to modify the bracket a bit to make it fit into the slider.
However, when I started putting everything together, I noticed a problem. With this new kit the cable sits almost 2 cm higher on the slider. Which means the cable won’t line up properly with the rest of the slider and the clutch handle on the engine.
On the Throttle cable, the situation would be even worse. So unless I modifiy the slider, the bracket of the slider and probably the mount of the bracket as well this is not going to work.
So I tried to put everything back together again, using the old parts. Only to notice that there was a problem. At the end of the clutch cable is a fork that connects to a handle on the actual clutch. I noticed that it did not have sufficient clearance on the handle. Which meant that as the clutch moved forward or backward, the fork would touch the handle and be lifted up, or pushed down. This puts additional stress on the clutch cable and clutch slider assembly.
So I modified the clutch handle. Simply grind away some bits with my angle grinder. I also noticed that with the clutch cable removed, the throttle handle on the steering stand moved a lot more easily. I always felt it was too stiff. I suspect that it was related to this problem. As the clutch engages, additional forces are put onto the two cables.
After the modification of the clutch handle, that problem was at least solved.
I took Sirion for a quick trial run on the river Merwede. The resonance has become a little less and occurs at somewhat higher RPMs as well. So some progress.
I kept Sirion at full ahead for almost 30 minute whilst watching the engine. It is really those big brackets attached to the engine on which the slide assembly is mounted that vibrate!. I will need to have a good look at them. Maybe I can weld on a reinforcement rib, or attach some lead to make it heavier (chance the resonance frequency). More work to be done.
Saw another Drammer 935, moored at the marina of Woudrichem. I am pretty sure I have seen this one, moored right here before.
Sirion performed flawlessly. No bits came undone. Back in the Marina I hosed her down and got everything tidy. If all goes well I will be leaving for Antwerp, first thing Monday morning. I am really looking forward to that trip!
Stay tuned.
Jeroen
Read BHPian comments for more insights and information.
