Engine vibration too much, need a seat to absorb it, on a bare metal bench

[chuser]

I have a 12' aluminum Jonboat and a 7hp air-cooled 4 stroke engine that vibrates the boat when it runs. I thought buying a suction cup boat pad for my butt would fix the problem, but if I run the engine for more than a half hour even that doesn't help. Is there some kind of special anti-vibration seat for rinky-dink boats like mine?

I've searched, and the all the seats that I see are meant for bass boats, and they have screws to mount to a chair. I don't have a chair, just the bare metal bench. I also see seats for center console type boats, which won't fit in my tiny boat. Is there a seat for my situation? The handle is a bit short and it gets uncomfortable sitting in the same place, so I like change hands which means I sit sideways or move around on the bench. Thanks for any advice!

 

[GA_Boater]

A clamp on seat mount with or without swivel is made for benches - https://www.iboats.com/shop/wise-boat-seat-clamps.html

Why does the motor vibrate so much and is it causing any damage to to the boat? Or maybe you're like the Princess and the pea? :lol:

 

[chuser]

I think it's just a cheap engine. I opened up the propeller assembly because Youtube videos on my engine said it shipped without oil and needed to be filled otherwise it would grind itself to dust, and what do you know it had oil in it. Stupid Youtube videos. Apparently I put something together wrong because after running for a while it wouldn't shift into gear. I took it to a local repair man and I guess he took the engine apart, because when I got it back it vibrated more than before.

That seat mount doesn't have shock absorbers or anything? It's just going to transmit the vibrations to whatever seat I mount on it. :grumpy:

 

[Scott Danforth]

a 7hp air cooled single-cylinder motor will vibrate like a dog passing a peach pit. my guess it is the one thats on ebay....its a chinese knock-off lawn mower motor on a chinese knocked-off lower unit.

buy a good used 6hp 2-cylinder 2-stroke outboard for less than you paid for the ebay special and it will run smooth

 

[GA_Boater]

That seat mount doesn't have shock absorbers or anything? It's just going to transmit the vibrations to whatever seat I mount on it. :grumpy:

An upholstered seat will absorb a lot of the vibration. There is always this - https://www.iboats.com/shop/garelick...on-system.html Now we're starting to talk real money and you still need a seat.

What about the vibrations through the tiller to your arm/hand?

Guessing this is the motor you bought or through one of the dozens of other ads for the same motor - https://www.ebay.com/itm/196CC-7HP-4...1&isGTR=1#shId You would think that the Chinese would hire some copywriters versed in the language of the target country. What in the world does an American flag, UPS, USPS, FedEx have to do with the motor? 2 year warranty, the ill-written text says 1 year. Contact times are Monday To Friday: 8:30 AM to 5:00 PM (Beijing China time)

I'm with Scott. Sell it for whatever you can get for it or try to return it if it's less than 30 days. Then buy a used 2 stroke.

 

[chuser]

Oh. I suppose I didn't mention I'm actually in China. I guess the profile location doesn't show in the posts. Imported engines are prohibitively expensive due to import tariffs. I've looked for secondhand sales on the usual sites but as far as I can tell they don't exist. There's little recreational boating culture here, boats are 99% cargo vessels or working fishermen. No taking the boat out to the lake or going angling. Can't swim or waterski or eat the fish when the waterways are polluted. I just got mine to putt around the canals in my city. The canals were how they used to transport goods before motor vehicles, you see. They still do, actually, I passed several boats full of watermelons the other day. Most Chinese cities are full of canals, but my city is unique because they actually allow private navigation. Usually the canals are off-limits to anyone but licensed users.

I'm stuck with the crappy engine. It was the most horsepower I could get for the price. Otherwise I would have been priced out of the market. People here who have powerboats are wealthy and bored and looking for something to spend money on, so they don't really care about the cost. A 6hp Yamaha engine is $1600 while my 7hp Hangkai was $350. I'm happy enough with it, it runs, it's not going to be an heirloom or anything, it's just that my butt gets sore after a half hour sitting on the bench with a cushion. That active seat suspension looks good but yikes on the price.

They didn't even have an English manual for the 7hp, the factory gave me a PDF for the 3.5hp and called it a day. I'm currently translating the Chinese manual, I suppose I'll post it when I'm done.

 

[SOG3]

What's wrong with a good , thick foam cushion ??

 

[82rude]

Gel filled auto cushion.

 

[GA_Boater]

Oh. I suppose I didn't mention I'm actually in China

If the home country doesn't support these motors, then all the warnings we give about buying these things is spot on.

 

[chuser]

What's wrong with a good , thick foam cushion ??

I bought one. It works, but after a half hour I can feel it.

Gel filled auto cushion.

Huh, OK I might try that one.

If the home country doesn't support these motors, then all the warnings we give about buying these things is spot on.

I'm sure it feels satisfying to tee off and hit one out of the park like this on me. They support the motors just fine. In fact, they support them greatly by tariffing imports in order to benefit their domestic motor manufacturers. It pushes the boat around like it was designed to do. I'm aware I'm on the low end of the market and things won't be as nice as engines that cost five times the price. I'm just looking for a solution to minimize the vibration issue.

 

[GA_Boater]

Warning - The word "tariff" and derivatives will not be used in this thread again. We do not allow political discussion in our forum.

Home country meant the manufacturer, not China. I should have been clearer.

In your contact with Hangkai, did they have any suggestions to minimize the vibration? A thick rubber pad on the inside and outside of the transom held in place by the clamp may help.

I don't know if there are any other seating suggestions we can make.

 

[Scott Danforth]

the problem is a quality single-piston air-cooled engine with a heavy cast-iron flywheel will shake like a dog passing a peach pit.

the knock-offs use an aluminum flywheel, are not factory balanced, and will shake like a dog passing a porcupine and its coming out backwards

its the nature of a single cylinder engine.

Not sure much can be done other than reducing the amount of vibration at the source. the best way to do that is to add a second piston like small outboards have had for decades.

the twin cylinders were not done for power, they were done to remove a significant imbalance.

 

[chuser]

OK thanks. The tip about putting a rubber pad on the transom may help. I'll try it. Thanks for all the expertise working for me, I appreciate it.

 

[Ats666]

How about isolating the vibration between the motor and the boat?
Does your transom have wood on both sides?
Is there room to add thick Heavy-Duty rubber on both sides of the transom to clamp down on?

Opps, missed the message about adding rubber

 

[chuser]

I got the gel hex-core pad for the seat and it works a lot better than just the cushion. Thanks for that advice. I also have thick rubber strips on order, I will put them on both sides of the transom clip and see if that helps. The vibration is pretty bad but I'm just lucky to have a boat at all. I put the word out for a used engine, but it's doubtful if any will appear.

 

[Old Ironmaker]

Attack the problem at the source first, cushion the transom mount however I'm thinking by the time you clamp down on it enough to secure the motor there won't be much foam to cushion the blow left, if any. How about if we put an inflatable hemerrhoid cushion ring on the bench, you might need it on a nice thick foam cushion too. Foam is probably your best bet plus a cheap seat clamped to the bench. I bet even covering the metal bench seat with thick wood, not hardwood, pine or similar, then a cushioned seat with more foam and a hemorrhoid ring. Wood is a good vibration absorber. After boating for an hour you might need the hemorrhoid ring at home. They are portable.