Ring 16ft chinewalks at high speed

[Toffy]

I own a 16ft English Ring Powercraft with a 140hp Evinrude 2stroke outboard, 3 blade prop. It does 65mph at 5900 rpm but gets really wobbly and dangerous at this speed.

This boat is a standard small waterski raceboat, no specific set up or tuning. Engine trim buttons on the steering wheel, foot throttle.
No watertank at the front (gastank is located there)
Trim tabs at the back are fix, yet I can change there angle after each run

What can I do to :
1/ reduce the chinewalking at high speed
2/ get higher top speed

Any help is appreciated
Thx !

[pyro]

The chinewalk must be controlled by dirver input, plain and simple. It will not fix itself altogether. Solid mounts and proper running height will help, but it will not cure it. V-hulls must be "driven."

The fuel tank up front is a bad idea. Fuel level will constantly affect handling. Trim tabs won't help either. It just offers more surface to bounce off the water once it starts getting away from you.

It takes practice...

[Ted Stryker]

Over time you'll develop an instinct on how to compensate for the wobbling with small steering movements that are opposite to the direction of the boat movement... When the boat tries to lean to the left, you have to quickly but not aggressively steer to the left... That is a very crude explanation, but the steering inputs will become well timed and very fluid with practice... Being corrected at just the right time, and just the right amount is the goal... Try not to over trim the engine, a good level trim or just under level may be a good starting point... Engine elevation is also a key factor, but I don't have any experiance with your hull in particular so I can't comment on exactly what height on the transom that it needs to be... Also try to remove as much slack as possible from your steering cables an system... Good luck and stay with it...

[delawarerick]

Is it a v or a rounded bottom?

[Alan Power]

Hi Toffy, welcome to scream and fly;)
To expand a little on what has already been said, V hull's do need to be driven, but correct setup can go a long way too.
I am in the process of setting up a Phantom 16 (almost the same boat) with a V6 merc at the moment with a friend, to race in the newly formed clubman class.

Solid upper and lower engine mounts will dramatically reduce the wobble in the engine and help reduce chinewalking.
Dual cable or hydraulic steering helps too, both from a safety point of view and it also helps reduce engine "play" contributing to chinewalking.
I would situate the fuel tank in the rear as it will allow you to get the bow up some and I wouldn't worry about the balast tank unless you plan on some rough water use.
Trim tabs are widely used on phantoms and rings to help balance the boat and keep it level in the rough, I don't have much experiance with these yet but if you ask some of the guys on www.boatmad.co.uk they will give you the scoop on these, they also may be able to sort you out with a cheap set of hydraulic tabs.
To gain a little speed you should look for a 5 1/2" jackplate (lots on ebay) and raise the engine a little but make sure you fit a water psi guage to keep an eye on your cooling water, raising the engine will probably help out with the chinewalking too. Also, what prop are you using now, look for a small ear chopper or an srx, these are both bow lifters and over hub props.
If you start to loose water pressure go back down on the jackplate a touch or fit a nose cone with lao water pick up, if you don't already have one.

Let us know how you get on and post some pictures of your boat too. 65mph isn't bad with little setup.

Best of luck,
Alan

[Toffy]

Hi !

Thx for the replys so far !!
Some more info :

Hull : is a V-bottom

Steering : is a brand new Ultraflex single cable steering, suited to the engine power. No hydraulic though, which I think would have been better and safer. I experience some slack on the steering : ca 1inch wheelturn. I believe this is minimal with single cable steering systems. I think I must be able to control it better... I'll need more practice...

Engine height, trim tabs, prop : I've never changed them. It 'looks' allright to me though. But I have no knowledge/experience in what the exact engine height should be. I'm a bit afraid I'll get a setup that's worse. Remember : I get top speed at 5900rpm, which is only 100rpm below max power...

Fuel tank : I bought the boat with fuel tank at the front. Previous owner installed a bigger 140hp engine which is quite big for this boat.
He had to install a bigger fuel tank and he had to find a solution for the front of the boat, which was pointing at the sky at standstill...
=> fuel tank at the front.
But OK, I DO experience changes in handling due to changing fuel level...

Conclusion : should I change engine height? Get adjustable trim tabs, or other size of trim tabs ?

Thx!
T.

[RichS]

Sounds like you have a stock motor with single cable steering. You will need to get solid motor mounts and dual cable steering if you want to be able to control the chine walking.

[Rickracer]

....and you can shim the stock mounts to remove some play there. Filling the voids in the rubber with aluminum shim stock can tighten them right up. A jackplate can help, (specifically, more engine height), and should allow more speed, but I'd avoid going back too far. A Bob's Machine MJ-5 would be just the ticket there, it can be set up as either 5.5" or 2.5" setback, and the extra weight of the plate is minimal. You might want to try an OMC Raker prop, if you can get your hands on one. I would move the fuel tank to the rear, and if you need weight up front, move something that doesn't change with consumption, like your anchor, equipment storage, or perhaps the battery. Obviously, try to avoid adding any weight that isn't necessary. :cool:

[Alan Power]

Pics of Toffy's boat...

http://forums.screamandfly.com/Gallery/showphoto.php/photo/8830/size/big/cat/3131

[86ENTICER]

Toffy I have the same problem with my 16' Chackmate with a 135 Merc. I am new to S&F and came on board looking for help and asking the same questions. "Good luck and that is a real sharp boat" Fred

[graemers]

Hey Rickracer, do you have any pics of the "shimming" you are talking about. Wouldn't mind doing that

[Rickracer]

But if you pull the cover off the lowers, you'll see voids between the metal shell and the rubber, that's where you want to shim. You could probably accomplish the same thing by cleaning out the openings and pouring them full of epoxy, or JB Weld. Shimming is quicker though. :cool:

[graemers]

Thanks, I'll take a look. the top ones I have to ge the powerhead off? When I do this, replace the powerhead gasket?

[Rickracer]

The top mount is of similar construction. :cool:

[225RANGER]

Hey Toffy, I have a 26" OMC raker. It looks new, never bent or dinged up. I use it for a spare, cause 4 blades work better on my heavy Ranger. I will let it go for $300 plus shipping.
Thanks,
Kevin

[Toffy]

Hey !

Some more info :

My Prop = Over/Thru-hub exhaust 3 blade propeller OMC Raker, diameter 13 1/2", pitch I don't know... but : according to http://www.a1discountprop.com/omcoutboard.htm
and knowing that my engine is a Evinrude 140hp from 1992 my pitch should be 18/20/22/24... I found no ref number on my prop... :-( but hey, I'm down to just searching (or measuring?) the pith... :-)
So 225RANGER, thx for the offer! but at the moment I'll just keep my current Raker prop, your 26 pitcher propably won't fit too, but it doesn't matter...

Jackplate : I have allready a 5 1/2" jackplate
I found also some slack on one of the bolts of my jackplate... (!!!!!)
It's a bolt that makes a connection of the 2 jackplate parts
Screwed it tight -> think it can already make a difference to my chinewalking problem...

Height of the engine :
With current setting of jackplate I see the enige is mounted practically all the way down in its mounting bracket sleeves... => plenty of room to lift it... Alan told me (look at picture in my profile pls...) it looks a bit low... (thx Alan!) I measured the propshaft centreline 100mm (=almost 4inch) below the hull bottom. Horizontal distance hull -> nose gearbox is 305mm (=12 inch)
Both measurements while engine is vertical (not trimmed at all) off course...

Conclusion : I think I'll lift the engine about 20mm. (Is this a lot??)
But there are 3 things I'm worried about:
1/ will I still get enough cooling water pressure ??
2/ will my prop ventilate while cornering ??
=> Think I'll just test to get the answers...
3/ I have some cracks in my transom, I see they got a bit worse since last year... I'll post another thread to discuss this problem...

OK that's it for the moment.
Thanks for all the help and tips so far !
T.

[Toffy]

You can find the thread about my transom-cracks problem at this link :
http://forums.screamandfly.com/forums/showthread.php?p=878192#post878192

Greets! T.

[pyro]

The prop may ventilate in the corners a bit, but the Raker is fairly tolerant of mild surfacing, so it shouldn't rev up and completely lose bite in the corners like a cheap aluminum prop.

You can seal off a couple of the highest pairs of intake holes to allow more height with good water pressure.

[Toffy]

Hi !

Thx for all your comments so far !
Here's another update...

The works we did so far :

we tighned up all bolts that connect the engine to the jackplate and transom. doing so we reduced some slack and we think it should already make a difference in the chinewalking problem...
we lifted the engine 15mm (=0,6 inch)
temporary repair on the transom see http://forums.screamandfly.com/forums/showthread.php?p=882521#post882521 (http://forums.screamandfly.com/forums/showthread.php?p=882521#post882521)
oil change gearcase
make a better connection for the fueltankWhat we still have to do :

reinstall the fuel tank
install new battery platform in polyamide
install new trim swiches on the steering wheel
block off the top pair waterintake holes (4 -> 3 pairs remaining)
determine the pitch parameter of my raker prop
lubricate the engine + test run
test accuracy of the rpm gauge by stroboscope measurement and adjust

We’ll hope to do a lot of these things this weekend.
But everything should be ready by the end of this month...


Questions :

I still don’t know the pitch of my prop : I have a pretty good guess it’s 24 but I’m not sure.Can I measure it ? Or should the ref nr be on the inside when I disassemble it ?
We lifted the engine 0,6inch. Should we already ‘feel’ this in top speed & handling ? Is this a lot ? Could you please comment on how it looks (pictures and measurements below) ?
Our rpm gauge showed last season 5900rpm at full throtlle. Now, for this season we lifted the engine a bit, but didn’t change our prop. We are already 400rpm above max power rpm. The engine is a ’92 stock Evinrude 140hp type TLENS with following rpm specs : Max rpm = 6000 , max power rpm = 5500 , full throtlle range = 5000 – 6000 rpm. Ignition stop kicks in at 6700rpm. All this according to my OMC Service manual for this engine. We will first make sure to have an exact rpm gauge reading !! This is essential.

ð Do we risk to blow up the engine if we go higher than (a correct measured) 6000rpm ? Or are these stock engines built to resist a bit higher revs ????
ð How long can we operate this stock engine at max 6000rpm ?? several minutes ??



I expect we will need an new prop, but we’ll test first…….


Some measurements before and after lifting the engine 15mm :<O:p</O:p

Vertical : propshaft centreline below hull bottom = 100mm (=almost 4inch) => now 85mm (=3,35inch)
Horizontal : distance hull to nose gearbox = 305mm (=12 inch) => now unchanged
Both measurements while engine is vertical (not trimmed at all)I’ve made some pictures ‘before’ and ‘after’ lifting the engine.
In the next post you can see more pictures ‘zoomed out’…

Bye !
Toffy

[Toffy]

The 'zoomed out' pictures after lifting the engine 15mm.
These should give you a better look on the height of the engine regarding to the bottom of the hull...

Greets, Toffy

[Alan Power]

I would think you could go up some more still and not loose water pressure! You can go a little higher with setback as the setback allows the water to come up to the prop as it's spaced a little farther from the hull. Also, the boat doesnt run flat like on the trailer, as the bow rises the prop gets pushed deeper. Have you fit a water pressure gauge yet, I would defo put one in;) I'm not sure what the safe red-line (max rpm) on that engine is, ask in the technical section here on the boards. The best way to test is to run the boat, bring some tools with you and if you still have water pressure and your happy with gaining some rpm, raise it a little more;)

Also, you should fill in your location in your user profile to let people know where you are;)

Alan

[Toffy]

Following link shows some articles about chinewalking and how to control it... Think it's usefull to anyone with questions about this topic.
http://www.bassboatcentral.com/new_page_2.htm

Greets, T.

[Alan Power]

Hey Toffy, thanks for that;) Any progress on your boat, have you taken it for another ride yet?

Alan

[Toffy]

Hi there !

Yesterday we did our first (test)run of this season... and it went fine...
Beautifull day, lot's of sunshine, lot's of boats... :cool:

the transom-repair looks still good after several runs, no extra cracks, no sounds, everything looks good and is sealed of well... : transom is OK for this season...

As mentioned earlier : we raised the engine 15mm + we tightened every bolt and mount on engine and jack plate + we made a solid new fixation for the fueltank (which was already) at the front.
The result was more or less what we expected :

a bit less chine walk, more controlable if you ask me, (but then again... maybe I'm just becoming a better driver :) )
a bit more top speed, although we didn't have proper measurement
great acceleration in a straight line (engine revs a bit more during acceleration)
poor acceleration while cornering due to prop-cavitation...So, worse corner acceleration, but also when we dropped too much speed in the corners, we could feel the prop lose bite in the water and revs went up... it pretty much ruines the whole experience... I am a bit surprised that 15mm engine lift would have this much of effect...

We also did some waterskiing and wakeboarding.
While I was wakeboarding I could feel that the boat was going faster, although the driver (my brother) said he was at the same rpm than previous season. I also could 'see' the cavitation plate and therefore almost the top of the prop. At the end of the day we inspected our Raker prop, still undamaged... :cool:

To be short : I think I'll drop the engine again, about 10mm or maybe the whole 15mm...

I talked to more experienced people at the club about installing other props... Got a lot of tips and advice... but I'm not able to 'filter out' the good tips... if you know what I mean... One said I could try a cleaver-prop, another one said I'dd better leave things like they are...
Anyhow, Do you think there's a better prop that has less corner cavitation ??? Any tips (from experienced people :D ) are welcome !

Thx, Toffy

[rockey]

i have 1995 16 ring with 90 merc 2 bolt holes up the transom bolted to back of boat no stand off bracket runs 24 ballistic prop runs true 54 mph on gps with sea star steering all the paly out of the mounts etc 12 gal front tank runs dead straight no chine walking i would but motor back on transom lift up a couple boat holes and loose the trim tabs un less your going to but bennet hydraulic tabs on which is what i have use the boat for skiing and blasting about thats mp 2 p worth good luck

[Alan Power]

Rockey, what's the boat in your avitar? Got a bigger pic of it? Looks sweet:D

Alan

[rockey]

it's a mike ring uk 22 cat nearly ready for the water

[Toffy]

Thx ! :cool:
See if I got this right ??
- loose the trim tabs : for speed runs
- reattach the trim tabs : for waterskiing, wakeboarding

I'm not so familiar with trim tabsettings, nor its exact purpose... I tell ya what I DO know at the moment :

First of all, my trim tabs or not hydraulic. I cannot change their angle during a run. I can adjust them after each run if necessary, simply by turning the turnbuckles. (see pictures earlier in this thread)
Last season I did some testing : I set the trim tabs all the way down. The result was bad : I got enormous wake and spray, and no topspeed.
I changed the setting again to an angle that they are more or less an extention of the hull. The result was fine... so I've never changed it again upon till now...

Now I come to think of it... : last sunday - while wakeboarding - I could see the trimtabs pushing down the water... I think that when I remove the trimtabs the water level after my hull would raise... Perhaps this can allow me to maintain my 15mm elevated engine-height ??

Questions : should I test doing a speed run without trimtabs ? :confused:
How will this affect handling in a straight line / while cornering ?
I'm not sure what to expect, so any help is appreciated !

Greets, Toffy

[Toffy]

BTW rockey, do you have pics of your ring ?? :cool:
Greets ! T.

[rockey]

what i ment re tabs i would lift them right up for fast runs and down a bit for skiing and rough water with hydraulic. you can adjust for this here are some pics

[Toffy]

16ft rings are not verry common... yours seems to be in excellent shape rockey :cool: . Btw, I also registered on boatmad.com as Toffy... you've probably seen me there... Greets, T.

[rockey]

yes very happy with the boat would like 90 yam they are more easy to tweek up but it go's very well:)

[Toffy]

Hi guys !

Yesterday we did some testing. Think we found the best possible setup now. Fast in a straight line and not too much prop-ventilation in the corners.

First we did a run with the engine 15mm higher than its original position. = same test as last week. My brother and I agreed this gave too much prop ventilation while cornering...

For the second testrun we removed the trimtabs + lowered the engine again about 10mm. (This means we are still 5mm higher than original setup). We found out that the trimtabs DO make a difference, but not a lot... : During highspeed run, it's a bit more sensitive to chinewalking without the tabs. Kinda logic cause our relative short 16ft boat becomes a bit longer with installed trimtabs... We were a bit surprised to see that there was practically NO differece in acceleration to get it planing.
The 10mm lower engine performed a lot better in the corners... Just a bit of prop ventilation, but not a lot..... It's just perfect :cool:

We did several GPS-speed measurements. We topped at 106km/h or 65,9mph with 3 people. Quite happy with this :D. Keeping balance and controlling the chinewalk are still the key factors at this speed. We always have to release the throttle to regain balance and therefore keeping it safe. I think 110km/h must be possible in perfect conditions (2people for less weight and good balance, reattached trimtabs for good balance and off course absolutely flat watersurface)

So, now we're gonna enjoy the waterski and wakeboard season!
For the future we'll consider putting on larger trimtabs and dual cable or hydraulic steering... we'll see !

Bye! T.:cool: