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Author Topic:   2008 170 MONTAUK Vibration
SC Joe posted 11-08-2008 05:32 PM ET (US)   Profile for SC Joe   Send Email to SC Joe  
I recently took my 2008 Montauk 170 with Mercury FOURSTROKE 90-HP engine to the local Boston Whaler dealer for its 20-hour service. Since purchasing the boat new in August, it has had a vibration at about 2,800 to 3,000-RPM. It's not horrible, but noticeable throughout the boat. It is more of a strong buzz than a vibration. I thought the propeller may have be out of balance or round, so I asked the dealer to take a look at this problem while it was in for maintenance.

The dealer said that he drove the boat and he felt the vibration. He changed the propeller and the hub, as well as placing diagnostic equipment on the engine while running at the affected rpm range to make sure the engine was running properly--all as sugested by Mercury. He verified the engine is operating correctly and to specs. He could not eliminate or even reduce the vibration.

He said he phoned Mercury and that they are aware of the [vibration]. They stated if the propeller and hub change does not fix the [vibration], then there is nothing that can be done. They explained that the vibration comes from the boat being "tight", and because of the all-foam construction, that any vibration in the engine is magnified throughout the boat. This honestly sounds like garbage to me.

The dealer also stated that he has seen this [vibration] at lower RPM (1,200 to 1,800) on other Boston Whaler boats, and that normally changing the propeller and or hub fixes the [vibration]. I questioned if it might be caused by bent or out-of-round shafts, and he said that this could not be the problem as that would manifest itself as a diferent problem. He added that the Dauntless 180 has been one of the worst he has seen for this problem, and that a propeller hub change normally fixes it. He invited me to call Whaler, which I will do, but I wondered if anyone else has had or experienced this vibration?

Unfortunately, there are no other Boston Whaler dealers within 100 miles of me, and they are owned by the same company (Hall Marine). Thoughts?

Jerry Townsend posted 11-08-2008 07:01 PM ET (US)     Profile for Jerry Townsend  Send Email to Jerry Townsend     
SC Joe - the vibration you notice is caused by the vibrating engine (they all do - to some extent) exciting a natural frequency of the boat/engine system. That boat/engine system involves the boat, the engine, any vibration isolation incorporated into the engine and the mounting of the engine on the boat. As such, this "problem" can occur at a variety of speeds.

With just a "... more of a strong buzz than a vibration ..." it should not cause you a problem - particularly since it occurs at an engine speed that you are typically going through - one way or the other. And the "buzz" can be coming from something, some component or the mounting of something in the boat. --- Jerry/Idaho

SC Joe posted 11-08-2008 07:53 PM ET (US)     Profile for SC Joe  Send Email to SC Joe     
I've never had a boat do this before.

Is it common to Whalers?

Jerry Townsend posted 11-08-2008 11:10 PM ET (US)     Profile for Jerry Townsend  Send Email to Jerry Townsend     
No - any rotating device - any engine, any wheel/tire - any rotating device - they are all potential sources of generating the vibration. And once the source is generated, other components/systems will vibrate, but the vibration will be enhanced around or at the component/system's natural frequency.

One thing you might do is to have your dealer check the mounting of the engine on the boat. I am not famaliar with the Mercury engines - and yours may have some form of vibration isolation built in - just another possibility.

From your words - I suspect that the problem is one of isolation - an unbalance of the engine/prop - being transmitted to the boat via the engine mount. But this is just one possibility. --- Jerry/Idaho

jimh posted 11-08-2008 11:30 PM ET (US)     Profile for jimh  Send Email to jimh     
The stiffness of the engine mounts affect the transmission of vibration from the engine to the hull. These days there seems to be a trend to use engine mounts that are more stiff than in the old days. I believe some of this trend is driven by a desire to reduce the appearance of any vibration in the engine. Older engines which have engine mounts that are more resilient often show a visually noticeable shake at low speeds. It seems like manufacturers don't want the customer to see any vibration in the engine, so the engine mounts are made stiffer. As a result the engine vibrations are coupled into the hull. This tends to dampen the vibrations and reduce any motion in the engine cowling. Of course, it also transmits the vibration into the hull.

I suppose that the stiffer the hull structure the less it will flex and absorb the vibration. A brand new Boston Whale hull is probably about as stiff a structure s you will find on the water. The result is the helmsman feels more vibration from the motor.

On the other hand, stiffer engine mounts generally help high speed performance, so they might also be beneficial in getting a little extra speed out of the boat.

SC Joe posted 11-09-2008 12:46 AM ET (US)     Profile for SC Joe  Send Email to SC Joe     
Perhaps I asked my question incorrectly.

Have you seen that Whalers show symptoms ("buzz" in the boat) of engine vibrations more than other boats due to foamed hull structure?

This Mercury engine runs as smooth as, if not smoother, than my previous engine, a Yamaha F150. That engine vibrated the boat at very low speeds (800 rpm), but it ws a vibration and not a buzz.

Moe posted 11-09-2008 06:23 AM ET (US)     Profile for Moe  Send Email to Moe     
The 2,800-3,200 rpm range you cite seemed to ring a bell, so I looked up the 170 Montauk's performance chart on their web site. It is as I thought--that range of operation of plowing through the water bow high right before the boat comes up onto plane and reaches optimal fuel efficiency at about 3,400-3,500 rpm.

What's unique about this range is that the outboard is usually trimmed full down hard metal to metal on the mount instead of riding on the hydraulic fluid of the trim cylinder. Try bumping the trim up off the full down stop when operating in this range and see if the buzz eases off.

Moe posted 11-09-2008 06:32 AM ET (US)     Profile for Moe  Send Email to Moe     
I forgot to mention... my vibration experience is with Harleys, in some cases the same engine mounted with soft rubber mounts as well as rigid mounting in other models. When allowed to shake with a rubber mount, the vibration is more the lower fundamental frequency. When mounted rigid, the frame typically resonates at a harmonic and the higher frequency vibration is felt as a hand/foot/butt numbing buzz. Our Whaler was the most stiff, rigid small boat I've ever been in. I likened it to being in a cast iron bathtub when I slammed it around in heavy seas.
Peter posted 11-09-2008 08:11 AM ET (US)     Profile for Peter  Send Email to Peter     
"Have you seen that Whalers show symptoms ("buzz" in the boat) of engine vibrations more than other boats due to foamed hull structure?"

I think there is some truth to this. Most other boats in this size are not made with the bonded foam sandwich construction. Accordingly, they don't have the same degree of stiffness and so the entire hull of the conventionally constructed boat tends to absorb vibration coming from the transom instead of transmitting through the boat where it usually shows up in the rails shaking, for example.

chuck21401 posted 11-09-2008 09:55 AM ET (US)     Profile for chuck21401  Send Email to chuck21401     
I have 2008 170 Montauk, haven't noticed much vibration except maybe idling along at 6 knots with the engine all the way down. Just a slight vibration. If it tilt the engine up a blip it seems to go away. I haven't noticed any unusual vibration from 2800-3000; the theory about all foam construction sounds bogus to me.

The last Whaler I owned (years ago) was a 15 Sport with a 2 cycle 48hp Johnson engine so the 170 with the 90 4 cycle is a big improvement in terms of noise/vibration!

Re: 20 hour check. I consulted with Merc on this topic and they don't require such a check but noted that dealers may offer it. My local dealer wanted $250 for this optional service.

SC Joe posted 11-09-2008 04:41 PM ET (US)     Profile for SC Joe  Send Email to SC Joe     
I'm going to call Merc and Whaler this week and see what they have to say about the vibration. I'll report back what they have to say.

As for the 20 hour service, you are correct; it is not mandated by Merc. But I am a firm believer in removing the oil used during break in, especially at the end of season. If there were any internal problems, hopefully the dealer would have caught them while changing the fluids.

sapple posted 11-09-2008 05:08 PM ET (US)     Profile for sapple  Send Email to sapple     
I have a 2007 Montauk with a Merc 90 fourstroke EFI. I also get the vibration at around the same rpm range. I definately noticed it since it did not happen with my Sport 130. However, since it only happens at an rpm range that I don't stay at very long I haven't worried about it much. (Should I ?) I just figured it was a quirk of this particular boat/motor combination. It usually happens when I am going up on plane and when I do, I almost always have the motor trimmed all the way down. Next time I am out I will try trimming out a bit before going up on plane and see what happens.
Jerry Townsend posted 11-10-2008 12:38 PM ET (US)     Profile for Jerry Townsend  Send Email to Jerry Townsend     
Another point - the vibration "problem" being discussed here is not unique to the so-called "Post-Classic" Whalers - as the problem will/can be felt in any "classsic" Whaler or any other piece of operating equipment. --- Jerry/Idaho
SC Joe posted 11-10-2008 02:11 PM ET (US)     Profile for SC Joe  Send Email to SC Joe     
I've never had any of the half dozen or so other boats I've owned over the years have this issue.
Jerry Townsend posted 11-10-2008 02:42 PM ET (US)     Profile for Jerry Townsend  Send Email to Jerry Townsend     
SC Joe - I have only had one other boat (a '74 +/- 13 Super sport with a 25 Evinrude) - which was so long ago, I can't remember any vibration problem. The only thing I am saying is that basically every piece of rotating machinery will have some vibration - and depending on the vibration isolation built into the engine - and the isolation of the mounting, a vibration may be detected in the boat. --- Jerry/Idaho
Feejer posted 11-10-2008 06:08 PM ET (US)     Profile for Feejer  Send Email to Feejer     
The only vibration have ever seen on my boat is sometimes the bow rail will vibrate when the engine is in idle. Usually if I bump the trim switch it goes away. The grab rail on the console of my Sea Hunt 202 with vibrate when the engine ran between 1000-1200 rpm, drove me nuts and I never could correct it.
SC Joe posted 11-10-2008 06:30 PM ET (US)     Profile for SC Joe  Send Email to SC Joe     
I called Whaler today and explained the problem and gave them all the pertinent info. He took my number and said he would be geting back to me.
Jerry Townsend posted 11-10-2008 08:51 PM ET (US)     Profile for Jerry Townsend  Send Email to Jerry Townsend     
Feejer - tighten your mounting screws a bit - or cut a "gasket" of thin plastic or rubber and put under the mount(s). This simply changes the natural frequency of that mount/rail/et al. --- Jerry/Idaho
Feejer posted 11-11-2008 10:17 AM ET (US)     Profile for Feejer  Send Email to Feejer     
Back in the spring I removed the entire bow rail. Just as you suggested I made a thin rubber gasket for each of the mounts. I then reinstalled everything. All the screws are nice and tight. It helped but I still get a little vibration at idle.
Jerry Townsend posted 11-11-2008 11:46 AM ET (US)     Profile for Jerry Townsend  Send Email to Jerry Townsend     
Feejer - that may be the best you can do. Any component will have a natural frequency at which it wants to vibrate. Our only choices of changing the frequency is the isolation of the mount or making the attachment softer or stiffer, or changing the mass. --- Jerry/Idaho
JoeyP posted 11-21-2008 06:08 PM ET (US)     Profile for JoeyP  Send Email to JoeyP     
The 150 Verado on my 190 Outrage also has some teeth chattering vibration at low rpms. I know I read somewhere that the 4 cyl four strokes 150 and 175 verados are rattlers.
SC Joe posted 11-21-2008 11:25 PM ET (US)     Profile for SC Joe  Send Email to SC Joe     
I phoned Whaler about the problem, and they called me back a day or so later. They said they had spoken to the dealer as well and verified the problem. Whaler said they had never seen a problem with the 170 and vibration at this RPM, and had no idea what was causing it.

The person I spoke to said he was going to raise it to the propulsion engineering group, and see what their ideas are, and then he would get back to me. That has been almost 2 weeks ago, and I haven't heard back from them yet.

chopbuster posted 11-22-2008 10:39 PM ET (US)     Profile for chopbuster    
Although not a 170 or a 90hp, my 60hp 150 Sport with the monolithic low profile bow rail, has absolutely no vibration.
Jerry Townsend posted 11-23-2008 04:33 PM ET (US)     Profile for Jerry Townsend  Send Email to Jerry Townsend     
Chopbuster - your low-profile bow rail will be "stiffer" and hence the natural frequency will be higher. Therefore, your rail would resonate at a higher engine speed - if at all. In general - the stiffer and the lighter a component/structure is - the higher the natural frequency will be.

And then, the isolation on your boat/engine may be more effective - which would reduce engine vibration from affecting the boat/components. ---- Jerry/Idaho

wezie posted 11-24-2008 08:41 AM ET (US)     Profile for wezie  Send Email to wezie     
Joe, you might write a letter to all the above and reference the calls and non calls. This sort of vibration, sound, etc most likely is not a problem; however due to your past experience with boats and that this one is causing you to question the situation, you just might want to create a paper trail, now.

Then there is the put your hand on it testing. If you have time and can get someone to drive for awhile; possibly you may be able to find exactly what is buzzing, by damping it. If it is in the cowling that is a bit more dicey.
With moving parts and electricity, that will be a question.

There is nothing like the old fashioned letter. They create files, and they imply formality and permanence.
I know some things can be a real pain, sounds like you need to share it with those that made it.

Good Luck.

SC Joe posted 11-24-2008 10:09 AM ET (US)     Profile for SC Joe  Send Email to SC Joe     
Actually Wezie, that's a pretty good idea, that I think I should do.
chopbuster posted 11-24-2008 05:57 PM ET (US)     Profile for chopbuster    
SC Joe;

The idea that BW was unaware of a 170 vibration issue
flies in the face of their having documented an R&D
solution for bow rail vibration beginning with the late
year 2006 model of the 170 montauk.

In this instace it appears as though the issue is not resovled.

See also;

In addition; search CW for "imko" for install info.

chopbuster posted 11-24-2008 06:20 PM ET (US)     Profile for chopbuster    
Hope this helps as well;

you need: 1 plate t=3mm , and about 0,5 mtr seamless
pipe Ø 22 x 2mm (316L)

Drill the holes from the clamp into the plate
Spot weld the pipe (same angle as other pipes)on the plate
Than weld it complete.

Use sealing under the plate (i used Sikaflex 221 white)

Than weld the other side on the bow rail.

You must measure the dimension for yourself. No whaler
or bow rail is the same.



sapple posted 11-24-2008 08:22 PM ET (US)     Profile for sapple  Send Email to sapple     
For the record, the "vibration" my boat gets momentarily at low rpm's is not from the bow rail. I would characterize it more like the whole boat shutters momentarily then stops once I pass through the sensitive rpm range.
Floodtide posted 12-01-2008 06:33 PM ET (US)     Profile for Floodtide  Send Email to Floodtide     
I made the above mentioned mod to my 2004 and it stiffened up the bow rail and eliminated vibration in small chop and at certain RPMs.

I found a local Cape Cod fabricator to do the work. He also noticed that the rail had a bend in it and he thought that eventually it was going to break.

He is a long time whaler owner and was surprised BW didn't make this stronger.

Traveller posted 12-01-2008 07:49 PM ET (US)     Profile for Traveller  Send Email to Traveller     
I think the modification that chopbuster made to the bow rail looks wonderful, and significantly stronger than the original design. On my 2008 170 Montauk, the bow cleat has been moved and is in a recessed area just above the anchor locker. I wonder how his modification would need to be changed to work with the 2008 bow design?
chopbuster posted 12-02-2008 12:50 PM ET (US)     Profile for chopbuster    

As much as I would like to take credit for the bow rail mod, it was done by IMKO another CW member whom I quoted in my original post.

chopbuster posted 12-02-2008 02:02 PM ET (US)     Profile for chopbuster    
Further reference;

SC Joe posted 12-08-2008 11:14 AM ET (US)     Profile for SC Joe  Send Email to SC Joe     
I just got a return call from Whaler. Basically, their answer was to live with it and there was nothing they can do.
GreatBayNH posted 12-14-2008 07:48 PM ET (US)     Profile for GreatBayNH  Send Email to GreatBayNH     
The bow rail vibration reported in Montauk 170s manufactured from 2002 thru 2006 was corrected mid-2006 with a bow rail modification (forward bow stanchions now slant closer together towards the bow). The Montauk 190s started production in 2007 with this bow rail modification so no Montauk 190 should exhibit engine vibration caused stanchion failures in the bow rail.

I was one of those that bought an early 2006 170 so I do not have the factory bow rail modification. I called Boston Whaler. They said my bow rail was fine and will not fail. I told them a few CW members reported forward stanchion failures in the bow rail and wanted to know what they would do for me when/if the forward stanchions welds fail. They said they noted the call and they would take it under consideration when/if the forward stanchions fail due to bow rail vibration.

Jerry Townsend posted 12-14-2008 09:40 PM ET (US)     Profile for Jerry Townsend  Send Email to Jerry Townsend     
Any vibrating rail system will fail - depending on the magnitude and frequency of the vibration and the time of service. In the engineering world, it is called fatigue failure. The modified rail system was probably made stiffer so that it's natural frequencies (and there are several) will be above the frequency of a vibrating engine.

SC Joe, I am surprised that BW took that long to respond to your call. I have only had one discussion with their technical people and they were right on it. But, basically, unless the magnitude of the vibration is pretty severe, there probably will not be a problem. -- Jerry/Idaho

fisherman posted 12-15-2008 04:07 PM ET (US)     Profile for fisherman  Send Email to fisherman     
I have a 2006 170 and experienced / solved the problem the same way as mentioned by Moe and Chuck21401.

Also you may want to check the thru bolts. I've noticed every fall that both the uppers and lowers require re-tightning by about 1/4 to 1/2 a turn. This past fall was the same.

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