Help with torque steer

[Brookp01]

Several months ago I changed my Mercury 2.5 200ish HP for a 2.5 efi nearer 300 HP. The new motor has a short offshore leg (15 inch I think) which has 2 inches of setback built in over the previous midsection. The gearbox is at the same height as before and the engine is mounted horizontally in the same position. Unfortunately I now suffer from an amazing amount of torque steer and it takes all my strength to stop it from turning right. I use wire steering which is turned round a drum behind the steering wheel, the wire then goes via pulleys in line with the drum down each side of the boat, through the back well, round pulleys either side of the motor which are attached to wings and finally fixed to a central point in the back well in front of the motor. The steering has not changed since the previous engine so I can only assume the torque steer is due to the setback and the extra horse power. Does anyone know how I can reduce this effect as the boat is becoming undrivable. Do I need to change the position of the pulleys on the engine wings to accomodate the set back? Do torque tabs work and if so how do I position them on the skeg? Does anyone know where to get electric power steering compact enough to fit behind the dash of an 18 foot phantom. Thanks in advance for any help it is much appreciated.

[roofer]

I run the exact same setup as you and have no problems at all, I did try a ss mid on my 18 phantom and it altered the handling so badly i went back to 20" mid.

[roofer]

Hello paul ive just realised who you are, welcome to boatmad.

[Cookee]

The batboats that use cable steering have bungees to help - we use hydraulic steering - I can recomend Seastar steering - you would need the "pro" for that setup.

[Brookp01]

Originally posted by roofer
Hello paul ive just realised who you are, welcome to boatmad.

Cheers Chris. Yes Steve said you had the same problem when you used that XR2 so I probably looking at going back to a 20 inch leg as well. What you doing with your Phantom at the moment?

[Brookp01]

Originally posted by Cookee
The batboats that use cable steering have bungees to help - we use hydraulic steering - I can recomend Seastar steering - you would need the "pro" for that setup.

Thanks. Off to try a 20 inch mid first then may have to look at power steering as a last resort cos it's expensive.

[roofer]

Originally posted by Brookp01
What you doing with your Phantom at the moment?

Just been doing a few mods to make it faster than yours , going to try and do the last few races at barrow and carr mill so probably see you there.

[Brookp01]

Originally posted by roofer
Just been doing a few mods to make it faster than yours , going to try and do the last few races at barrow and carr mill so probably see you there.

You may not need any mods to be faster than me cos I can't hold the boat in a straight line at the moment. Hope you make the last few races, the next 2 are Sundays though 8th Oct at Barrow and 16th Oct interclub at Carr Mill.

[roofer]

I bet your problem is the 15" mid, when i tried the shorty it altered the centre of gravity and the steering was a nightmare , at least swopping mids is a cheap fix.

[JamesM]

Its not the extra set back as although the 15 inch mid does have an extra two inches of set back, for the gearbox to be at the same height as before the saddle brackets must be 5 inches lower on the boat and due to the angle of the transom 5 inches lower will mean 5 aproximately 2 inches further forward. So it should have roughly the same amount of setback as before with the power head 5 inches lower. It could still be the mid though but for another reason, no idea what though sorry!!!

I would have said its down to the increase in power and revs but as roofer said his is fine with a 20 inch and was bad with a 15 and he's got more power than you can poke a stick at!!!

Have you tired some different props? How high is the motor, surface piercing?

Heavy steering is often associated with running the engine very high surface piercing props.

Torque tabs do work to a degree but I dont know know much about fitting em.

[scottyboy]

Brookp01, You wanna sell the 15" mid and gear box?

[Brookp01]

Originally posted by Johnny Boat Dude
Its not the extra set back as although the 15 inch mid does have an extra two inches of set back, for the gearbox to be at the same height as before the saddle brackets must be 5 inches lower on the boat and due to the angle of the transom 5 inches lower will mean 5 aproximately 2 inches further forward. So it should have roughly the same amount of setback as before with the power head 5 inches lower. It could still be the mid though but for another reason, no idea what though sorry!!!

I would have said its down to the increase in power and revs but as roofer said his is fine with a 20 inch and was bad with a 15 and he's got more power than you can poke a stick at!!!

Have you tired some different props? How high is the motor, surface piercing?

Heavy steering is often associated with running the engine very high surface piercing props.

Torque tabs do work to a degree but I dont know know much about fitting em.

Thanks for the info. I think the gearbox/cavitation plate is at the same vertical height as before just 2 inches further back, as the transom has been cut down to accomodate the lower saddle position. Usually I run a 24inch pitch 14.5 inch diameter chopper but tried a 26 inch pitch 14 inch diameter Yamaha prop to attempt to reduce the torque steer. The Yam prop slipped very badly on corners and revved 700 rpm more on the straight (8000+ with little trim, bit too much for comfort) with only a slight improvement on the steering. I'm borrowing a geerbox with a torque tab so will have to see what happens.

[Brookp01]

Originally posted by scottyboy
Brookp01, You wanna sell the 15" mid and gear box?

Not just yet I'm afraid, need to see if the 20" mid makes any difference

[hutchy]

dont forget your props,cheers steve

[Brookp01]

Originally posted by hutchy
dont forget your props,cheers steve

Ah! The props thanks for reminding me. Should be fun if you try the chopper with the current setup make sure you have a lot of water to your right.

[Cyco]

Why not try a different prop fisrt before altering your set-up.
What speed / revs are you seeing at the moment?
Try a ET lightning if you can get your hands on one.
Or try a small hub lazer 11.
What gear ratio are running.
I had all sorts of torque steer problems with my P20 when it was on ride guide steering, used to lock up when flat out with a 2.0lt
that was running a chopper prop as it meant to be the quickest prop for the boat, quote from the previous owner.
After trying several differnet props and changing the set up of the boat I gained 3mph and had no handling problems using a ET lightning (I did have the prop worked 3 times at prop rev to get it bang on).

Cyco

[Brookp01]

Originally posted by Cyco
Why not try a different prop fisrt before altering your set-up.
What speed / revs are you seeing at the moment?
Try a ET lightning if you can get your hands on one.
Or try a small hub lazer 11.
What gear ratio are running.
I had all sorts of torque steer problems with my P20 when it was on ride guide steering, used to lock up when flat out with a 2.0lt
that was running a chopper prop as it meant to be the quickest prop for the boat, quote from the previous owner.
After trying several differnet props and changing the set up of the boat I gained 3mph and had no handling problems using a ET lightning (I did have the prop worked 3 times at prop rev to get it bang on).

Cyco

Cheers, have recently tried a Yam prop to sort the problem without luck (earlier post). I run 1.87/1 gears, pull 7500 with medium trim using a 24" pitch 14.5" dia chopper and 8000+ with little trim on the 26" pitch 14" dia Yam prop. Huchy is going to try a 20" mid section on it and a gearbox with a torque tab. If this fails then another look at props may be on the cards.

[Cyco]

You have the prop already that can be cut to an ET lightning.
Contact Prop rev on 01202 671226 speak to Brian
They can turn your 24 x 14.5" chopper into a ET lightning replica.
This will work fine, and as I said previously this is quicker and easier than changing your mid section and gear box.

What top speed are you seeing on GPS then, and do you often reach that top speed whilst racing in the docks.


Cyco

[Brookp01]

Originally posted by Cyco
You have the prop already that can be cut to an ET lightning.
Contact Prop rev on 01202 671226 speak to Brian
They can turn your 24 x 14.5" chopper into a ET lightning replica.
This will work fine, and as I said previously this is quicker and easier than changing your mid section and gear box.

What top speed are you seeing on GPS then, and do you often reach that top speed whilst racing in the docks.


Cyco

Thanks very much I didn't know that the chopper could be cut to an ET replica. The boat is already on its way for the mid section and gearbox change and test, but the ET idea does sound preferable. Do you know what is in the cut that reduces the torque steer? Unfortunately I don't have a GPS but there are 2 reasonably long straights in the dock where I would be surprised if the boat didn't reach mid 70s or even nudge 80mph on both. This is a guestimation based on other boats though.

[Cyco]

Blade area and shape is what reduces torque steer with an ET