chine walk

[macutty]

hello all....my first post here so be gentle...;)

I have an '85 Carlson Glastron CVX-16 with an original '85 Merc 150 BlackMax. I have been running a 21" highfive for several years but just swapped to a 3 blade 21" SS to see how I liked it.

Now I did like the fact that the mid-range really seemed to pick up, but I have an issue with chine walk creeping on around 60MPH and getting uncontrollable not too much past this (61-62) where i have to let off or lose it.

There was chine walk with the highfive but it definately sems more pronounced with the 3 blade and I just ebayed a 24" chopper which should be here in a couple days so I'm looking for ideas on how to prepare for even mroe speed and I'm expecting more chine walk.

What (if any) remmedy's are there for chine walking? I've been boating for about 15 years but am just now starting to want to go fast and don;t have a huge knowledge base to work from...

Would trim tabs be of any use in stablizing the hull?

I do run alot of positive trim as it seems this is the only way to increase the rpm's and mph once I hit WOT. The motor is mounted as low as it can go on the transom but I only have 2 holes I could move up so should I be looking at a jake plate instead?

Any thoughts would be appreaciated.

Cheers

[Bogman]

Macutty

I'll be the first to welcome you and say " fill out your profile " ;)
There's a ton of stuff on this in the achives so you might want to do a search on the subject, it's a common question. A jackplate is a good idea if your looking for more speed but watch your water pressure when raising the motor !! Good luck with setiing up your Glastron.

Dan

[drasticplastic]

You need to put the motor on a CMC jackplate and set it up so the propshaft is 2" below the botom of the pad. This will be a good starting point with the 24" chopper. Right now the motor is to low. You will need to plug the top 2 water pick-up holes on each side of the gearcase and drill out the other remaining holes a little bigger. This is so when you put it on the j/plate and jack it up you still get good water pressure. I had one of those hulls with an slightly modded XR2 merc./24" small hub chopper. Very fun boat, would run in the upper 60's.

[beer30]

You need to check your steering for slack, also how are your engine mounts? They need to be stiff. These are two items that will cause chine-walking, if not up to snuff. :) Chuck

[macutty]

thanks guys. I'll take a look at the steering slack and motor height first.

If I go through the effort of modding the water pickups would I smart to also add a Bob's nose cone for the low-water pickup? Or is this uneccessary?

[86 apache 22]

I am following this thread because I own a chinewalking monster. What I can tell you is that tabs will do nothing for chinewalking. I have k-planes on my 22' Apache and when she starts to chinewalk the only thing the tabs will do is to bury the bow if you want. Yes, chinewalk stops but so does speed. Save the $$$$ if that is the only reason.

[beer30]

thanks guys. I'll take a look at the steering slack and motor height first.

If I go through the effort of modding the water pickups would I smart to also add a Bob's nose cone for the low-water pickup? Or is this uneccessary?

A nosecone would probably slow you down. Chuck

[delawarerick]

Does the cvx have a rounded pad? What type of bottom if im not mistaken its got a rounded pad. Rick

[pyro]

Solid mounts and tight steering are must-haves. Besides those items, you can't really "fix" chinewalk, you have to learn to drive through it.

[gotboostedvr6]

I have a CV-16,you run positive trim because that bow needs to be out of the water, to do this w/o trim you need setback around 4 - 5". When running wide open Lift the motor till you lose water pressure than drop it 1" this will be the max height you can run

[drasticplastic]

The CV-16 have a rounded keel, the CVX-16 has a flat pad bottom. Yes, as other have stated you need good steering cables and eng. mounts. A nose cone not needed in this application.

[trashy]

Setup can help some, but it really takes some seat time to learn how to control it. The LAST thing you want to do is jump off the throttle when it starts to walk. Instead, just bump the trim down just a bit and EASE off the throttle. Do a search for "chine walk" and you will find a bunch of information.

[macutty]

thanks everyone....I have some time at ther lake this weekend s we'll see how it goes.

Cheers

[Jimboat]

macutty - Your situation sounds pretty typical for a performance vee hull. You may also wish to check out the article - "Hump Zone - Why Does Your Boat Porpoise? (http://www.aeromarineresearch.com/adverts/HotBoat_April2007.html)")

I am currently working on an article discussing 'chine walking', so here are some specifics to chine walk...

Chine walking can arise with most high performance vee-hulls. As the hull accelerates, lift increases and the wetted running surfaces that are required to support the hull are reduced (more Speed = more Lift = less Surface). As the speed increases throughout the velocity range, the hull often gets to a point where the lifting surfaces become very much reduced and the hull is now “balancing” on a small area of the vee-portion or the “vee-pad” of the hull. When that surface becomes sufficiently small, it becomes very tricky to “balance” the hull on its vee or pad. The result is a rocking of the hull from side-to-side, from port-chine to starboard-chine, back and forth. This rocking can tend to get a little more extreme with each motion, and so the “balancing” must then be provided by additional driver (steering/throttle/trim) input in order to maintain the hull in a balanced state.

If left unchecked, the boat will rock from side to side with increasing drama. This is because the boat is now “inherently unstable” – meaning that if left alone, the “imbalance” of the hull is more likely to get worse on it’s own, not better (the worse it gets, the worse it gets). If it gets out of hand, you can get into real trouble!

So the hull will rock from port chine to starboard chine – back and forth – with more motion and faster motion. This is called “chine-walk”. With some driver input, the condition can be stabilized. With changes to hull setup and/or changes to the driving technique the condition can be alleviated.

Note that the notion that chine walking can be “driven through” without making adjustments is a dangerous approach. Make the proper setup changes first. With experience, you can then learn to make the subtle steering, trim or throttle adjustments that might control the condition – but don’t try to just blast through the onset of chine walking, as this usually ends up to be a very wet conclusion!

Chine walking is predominantly characteristic of vee-hulls with deep Vees (more deadrise), hulls with deep or narrow running pads and hulls, with a Veed pad or no pad (straight vee). These bottom designs are just more inherently difficult to balance at higher speeds. Another contribution to chine walking can be seen at higher speeds from "propeller slap" (usually seen more with props of fewer blades). As the prop turns, each blade enters the water and another exits the water. This irregular in/out of every blade, changes the dynamic forces at the location of the propshaft, repeatedly putting an imbalance on a hull that is trying desperately to balance on it's vee or pad, and ultimately initiates chine walking.

Setup of your hull and driver “seat-time” are the best solutions to the problem. Usually an alteration to the hull, or hull setup and/or modification to your driving methods (read seat-time) will improve the problem.

Here are some established steps toward minimizing chine walking:


Some established steps toward minimizing chine walking:
1. Check & adjust steering
2. Use solid mounts
3. Clean Hull Lines
4. Weight balance of hull
5. Motor height
6. Propeller selection
7. Seat time (experience)
8. Minimize Trim Angle
Summary: Optimize Hull Setup and Driver “seat-time”!

Check out more of the details in the full article here (http://www.aeromarineresearch.com/publications/HB_Jan2008.html).<O:p

[macutty]

for steering I temporarily have a single cable Uflex Rotech I had to throw in because it was the only thing within 300 miles that would fit when my original rack and pinion cable snapped on vacation a couple weeks ago. Is this type of system any good? should I stick with the rotech when I change to a dual cable setup in the fall or should I use another type/brand?

Also where might I find instructions on how to adjust the slack out of this system? like an idiot I tossed the instructions after I got it in...

[Techno]

Dual cables take the slack out. I don't think you'll ever get the slack out of a single cable system, one reason for the duals. The other is redundancy if a cable breaks.

Several people have mentioned the cure for chine walking several ways but it might be a bit mystifing to you still. Seat time and all that. Think of a bike. You fall to the left so you steer to the left, the bike stays upright. Falls to the right you steer to the left. On a bike you do this without thinking about it with the correct amount and some body weight. On a boat no body weight cheating.
So if the steerings a bit sloppy your instictive correction is lagging and possibly over reacting, increasing the rock you tried to cancel. The seat time is learning the reaction you do while riding a bike.


with increasing drama:D I particularly liked the way that was phrased.

[macutty]

Gotcha.

I do think more time at speed wil help, but I think firs things first, I need that dual cable setup and those solid motor mounts. As it is there is so much slop in the steering it almost feels like everything is a delayed reaction.

Any thoughts or opinion on the rotech system? Knowing this has to go asap what should I buy for the dual setup?

Cheers

[Jimboat]

If anyone has any good photos that show chine walk or your hull balanced on it's vee or "running on the pad", let me know, and I will try to include some of your boats in the finished Article (http://forums.screamandfly.com/forums/showpost.php?p=1148482&postcount=14).

[blacktruck]

I would get a dual cable for safety sake. In addition to the above description, the chine walking is because the motor is too low. those hulls are good. As you go faster you're lower unit drags, and the lower unit acts as a pivot, which is why the boat chine walks. By lifting the motor you are reducing the drag alleviating the chine walking. A lift would be the best, if it is not in the budget you can mount it higher for the time being. I would recommend trying a laser 2 prop. By anticipating the chine walking with the steering and adjusting accordingly you should have no problem keeping the boat steady. Solid mounts would be a good investment too.

[tunnelfast]

I agree with Pyro and Jimboat - solid mounts, dual cable or hydraulic steering will help alot. Jimboat's article sure covers the gambit.

Sorry Jimboat, I don't have any good pictures here at work. But I am sure some body must have a good pic of a vee boat balancing on it's pad or flying on the vee!

[Jimboat]

No problem, tunnelFAST...the article on Chine Walking is going in now...if you come up with any pics, just let me know, and i will see what i can do.

[scud]

I agree with pyro, learn how to drive a vee hull with pad , it takes practice !!. In the 80s I used to rigg bass boats and then demonstate the boat to the customers before they took posession .Make sure you firmly brace yourself .Having a gas pedal so you can keep both hands on the wheel helps . After a while when you get in the boat and drive you wont even realize you are correcting !it becomes reflex. Ofcourse your equipment should be up to par such as mounts , steering ect.

[miami14680]

Interesting!!!!!!!!TTT

[LSaupe]

Hey Jim:

Do you have a direct link to your finished article? Cant seem to locate it on your website for some reason.

Many thanks,

Larry S.

[Team Stream]

Use a dual cable,

[hsbob]

i would not want t run that rig with a single used cable system. there is too much torque on the system and when you start walking it gets higher. you need a dual cable or hydraulic [$12-1400 us].

those are really good looking boats but do you want to put that kinda money into it without having a pad bottom.

[rossi]

Everybodys right about the equipment you need that will reduce chinewalk but it won't eliminate it. There is a techniqe to driving a pad V through chinewalk and if you don't have a "feel" for it then it will be hard to overcome, especially in that Glasstron as they were desighned to be a nice ski boat. I've known people who had pad v's for years and just never got the hang of it "but they gave up after a few close calls". I've never been in a CVX with a V6 but I have been in one a few times with an inline 115 Merc (brown stripe). This dude has a CMC plate and runs a 24P chopper I believe. If memory serves me right he ran the high 50's, although he was sure it was the low 60's. Get the boat set up properly and be fluid with the wheel...don't muscle it.

[Streamin101]

A cvx-16 with a 150 is about maxed out in the low 60s. Chine walk is how the boat reacts to the decrease in wetted surface area. Driving a v-pad is a balancing act, the boat must be balanced on the pad by making small steering imputs to correct the chine walk. When the boat leans to the right turn the wheel slightly to the left with a very fast movement and opposite when the boat leans to the left. Start at the speed that the boat just starts to chine walk and once you have balanced the boat at that speed you will be able to drive faster without chinewalk.

[Quinten]

I'm sorry, but the words "turn the wheel" and "very fast" should not be used in the same sentence when referring to a boat running in excess of 60 mph. Even though the word "slightly" is included, those two terms should not be synonymous (spelling?) with each other. As rossi said "fluid" is important and a much better word. I think I know what you mean Streamin, but it reads kind of scary, especially if you're giving direction to someone who is not experienced with driving a boat at high speed. Just my $.02

[whipper]

This is an old thread im sure he has mastered it buy now.:D seat time!

[Quinten]

This is an old thread im sure he has mastered it buy now.:D seat time!

Man, you can see where I've been keeping my head at. Didn't even notice how old this was:) :o :D

[ssv1761982]

That is a sweet little boat. He had it at the NW rally in Washinton on the Columbia river.