Do the chine walk

[maverickofpoole]

I have decided to now keep my boat and want to carry out a few upgrades one of which is change my outdrive....I think.

Nothing wrong with my current outdrive other than its now approaching 10 years old. The boat is brilliant however it does have a tendency to chine walk on the port side when on the plane. Trim tabs do the job of putting us on an even keel however I am fed up with constantly adjusting the tabs. The current outdrive is a Bravo 1 with a large 4 bladed 18" prop connected to an inboard that will spin at 4400 rpm flat out. Cruising revs are about 3200for 22-25knots

My question is would changing my outdrive to a Bravo 3 alleviate or at least help the listing problem or would I be better off investing in auto trim tabs.

BTW I know it makes no financial sense to change a perfectly working outdrive but then owning a boat has never been sensible. I do though like my toys

All and any advice welcome

Martin

 

[2_rollocks]

I've got the bravo 3x drive which has twin props and the boat rides without issue unless I have some extra weight on one side which is quickly countered by the trim tabs.

The only experience I have of outdrives is with twin props as my last was a Volvo 290 duo prop outdrive and before that was ribs.

Will be interesting to find out if it makes a big difference or not.

 

[rhino_mac]

Excuse me for asking but what do you mean by Chine walk? I have a Monterey 250 with a bravo 1 on a Yanmar diesel. When planing the boat tends to heel or tip to the left by a few degrees which feels decidedly odd.

The local marine engineers have told me this is normal on American sports cruisers and to use the trim tabs to level the boat. However, I don't have trim tab indicators (being retro fitted next month) so this can be awkward at speed if you happen to adjust them wrong and forget which tab is where.

Would be interested to hear if this is the same as your issue and how you resolve it!

 

[maverickofpoole]

Excuse me for asking. When planing the boat tends to heel or tip to the left by a few degrees which feels decidedly odd.

Chine walk is exactly what you say. A lot of deep V single engined hulls have a tendency to lean/chine walk usually to port. Some also lean into the wind.

I am also looking forward to hearing from those more experienced than me (that will be most on here) on their thoughts/experiences

Martin

 

[Kawasaki]

I have decided to now keep my boat and want to carry out a few upgrades one of which is change my outdrive....I think.



Martin

No Martin
Don't go to the expense and trouble of changing your outdrive to cure your boat's handling
An outdrive is an outdrive imho
Cos of what I do
Teach peeps to handle/drive boats etc
I have helmed quite a few
This is not a Monterey nockin post
However I have noticed the Marque is quite susceptible to the the phenomenom to the symptom you describe
With Sports boats of this size/length etc .
I suppose it's a kinda of trade of ref performance and hull efficiency etc etc
Like getting up on the plane
The ride quality
The 'seaworthyness' and all that
Martin, I am no hull design expert, far from it
There are loads of peeps on here with better qualls than me in that respect
What I trying to say in my long winded style
Is
Try a prop change maybe?
Depending on how you use the boat
IE
For belting along
Or for just cruising about etc
Sports boats in general are no good unless planing
That is their forte
I have found that just trimming the outdrive a tad and then playing with the the trim tabs to level the job out works best normally
Gauges to look at are just a pain in the butt!
Best to just 'feel' how the vessel behaves imho
Cheers
K

 

[rhino_mac]

Nice to know there's nothing mechanically wrong with the boat anyway. Just a case of **** handling!!

I'm hoping that remembering to trim the leg up a bit from full down (which I always forget) and knowing where my trim tabs are so I can adjust them accurately will help knce the boat goes back in the water next season.

 

[Kawasaki]

Nice to know there's nothing mechanically wrong with the boat anyway. Just a case of **** handling!!

Top Tip!
Trickle out of the Marina / berth politely
Ok- I know you do, before hitting the Hammer

Outdrive trimmed 'In'
Tabs-- 'neutral' or 'bow down'
Tabs are a weird thing ref their 'description on the 'dash' with various boats from different Countries, it aint a 'given' m8!
You deffo have to play with them to get the feel of whats going on
However the trim of the outdrive is paramount first
Play with the 'leg' first, then 'trim' as the word suggests the trim tabs for optimum balance of the hull at a given speed
Buggerin about with two tabs an an outdrive will certainly confuse the issue if done all at the same time
People load and fuel load
And certainly booze load will feck the job up two!

Plus sea state etc
Remember- it is so unlikley that two days on the run have the same sea state and wave format
Same as yer brain after a few the day before

 

[Kawasaki]

and knowing where my trim tabs are so I can adjust them accurately will help knce the boat goes back in the water next season.

Hey up
Do yourself a favour
Whilst the boat is out of the water
Get swmbo
Or whoever
To operate the trim tab controls
Whilst you blimp the feckers
Get the 'operater' to tell you what the dials say as you watch the ups an downs etc
3 or 4 things will be checked
The dials tellin the truth
The tabs doin what they should do
Yer brain gettin yer head around it
Plus communication betwixt partner/ wife is still reasonable

 

[Chris_d]

I used to have a boat that did this, a duo prop is supposed to help cancel out the prop torque but not always there are so many other factors. I did change from a RH to a LH prop, was easy on the BMW outdrive I had just flip the control cable over on the top of the gearbox to go everywhere in reverse This meant the prop was now canceling out the engine torque effect on the hull, however the problem was not comlpetely eliminated, had to move a lot of stuff around which fixed it.

 

[oldgit]

More to do with hull design/size than drive.Poss high engine power torque verses size of boat.Torque givng the list simply due to the small hull volume less able to resist the prop force acting apon it.?

 

[Cookee]

First of all "Chine Walk" is when the boat rocks from side to side, sometime violently. What is happening here is just a result of too much prop torque or poor trim.

When an outboard or inboard is trimmed in too much it will always lean to one side (port with a standard rotation prop), trimming the drive out should help with this and trim tabs should only be necessary when there is a side wind or both together to keep the bow down.

I would suggest finding a nice flat bit of sea with little wind and experimenting with the effects of different trim settings on the drive without using the tabs - you should be able to find the sweet spot. If you're still having problems changing the prop may help, call a good prop company like Steel Developments and give them all of your details and they may be able to recommend a better prop.

 

[Nick_H]

Auto tabs can bring their own problems, and i've ended up disconnecting mine.

The issue is that operating tabs not only levels the boat, but also steers it, so the driver then steers slightly the opposite way to hold course, but this causes the boat to lean slightly into that turn, so the tab on that side operates, which causes the boat to turn more, so the driver corrects the steering and so on. I think the issue is more pronounced on deeper V hulls, and depends how much your boat heels into turns.

 

[l'escargot]

Chine walk is exactly what you say. A lot of deep V single engined hulls have a tendency to lean/chine walk usually to port. Some also lean into the wind.

I am also looking forward to hearing from those more experienced than me (that will be most on here) on their thoughts/experiences

Martin

What you have sounds more like a trim issue that hasn't actually reached a speed to develop into full blown chine walk. Chine walk throws the boat violently from side to side, alternately chine to chine, leading to loss of control if speed isn't reduced. Not all chine walk can be trimmed out as it is a factor caused by hull shape.

 

[scottie]

I have to say that my idea of chine walking was when the corner of the chine started to dig in and try to steer the boat which then could cause the boat to go out of control if over corrected as alternate sides dug in ie a design problem which should not happen .

The question of prop torque being a different animal altogether which is overcome with contra rotating props either duoprops or twin screw installations.

 

[Scarron]

Chine riding

Chine walk is exactly what you say. A lot of deep V single engined hulls have a tendency to lean/chine walk usually to port. Some also lean into the wind.

I am also looking forward to hearing from those more experienced than me (that will be most on here) on their thoughts/experiences

Martin

Sorry to be picky but what you describe as a tendancy to sit on one side is called chine riding. Chine walking is when the boat flips from chine to chine quite quickly and can be quite alarming, usually a phenomenon found in light weight well powered outboard boats when the drive is trimmed out a long way.

Your chine riding is probably a symptom of the a big single prop, potential cures could be prop work, change to a different type or number of blades to get more or less bow lift ( find a real expert) perhaps an automatic trim sensing system for your tabs and leg, or change to a bravo 3.

Hope this helps

 

[AndieMac]

I agree with Kwacker and Cookee about the leg trim angle probably needs adjusting out slightly, but from what I have seen of locally produced similar sized boats with the same drive units that have suffered the portside 'lean', they run more laterally stable with the simple addition of a (genuine) Stingray Hydrofoil.

 

[MapisM]

Sorry to be picky but what you describe as a tendancy to sit on one side is called chine riding. Chine walking is when the boat flips from chine to chine quite quickly and can be quite alarming...

Mmm... I don't disagree with your description of chine walking, but I've always heard chine "riding" used to describe the very same effect.
What the OP is describing is a plain and simple listing, which is not unusual at all with any single engine/single prop boat.
As Cookee said, typically to port side, with a standard (R/H) prop.

In the OP boots, I'd just live with that. Fitting a B3 outdrive could possibly cure this specific effect, but it isn't worth the cost imho, not to mention the more than likely loss of a bit of top speed.
One thing the OP might wish to try is a L/H prop (with the same specs, of course).
B1 outdrive (as opposed to Alpha) can be used at WOT in both directions, and using a L/H prop is simply a matter of reversing the cables on the throttle lever.
Which btw can be done after the test, if the L/H prop would eventually give better result: the test as such can be simply done using the throttle lever in reverse to go fwd, and in forward to reverse.
Not the most user friendly throttle behaviour, of course, but that's the quicker and easier way to see what happens with a L/H prop.

 

[Scarron]

Do the chine walk yeah.

Seems everyone is thinking along similar lines.

The other thing you can try is fiddling with load distribution. Move all the heavy portable stuff over to the starboard side, then if that helps perhaps consider moving the batteries over?

 

[vas]

Seems everyone is thinking along similar lines.

The other thing you can try is fiddling with load distribution. Move all the heavy portable stuff over to the starboard side, then if that helps perhaps consider moving the batteries over?

sorry i'm ignorant on that sort of thing, but from a physics/mechanics pov wont moving loads around make the craft list to the other side when stationary? Is that acceptable?

cheers

V.

 

[Chris_d]

One thing the OP might wish to try is a L/H prop (with the same specs, of course).
B1 outdrive (as opposed to Alpha) can be used at WOT in both directions, and using a L/H prop is simply a matter of reversing the cables on the throttle lever.
Which btw can be done after the test, if the L/H prop would eventually give better result: the test as such can be simply done using the throttle lever in reverse to go fwd, and in forward to reverse.
Not the most user friendly throttle behaviour, of course, but that's the quicker and easier way to see what happens with a L/H prop.

Worked for me see post #9