Leaning boat

[Brettoh]

Ive a little 5.5 sailfish> Ive noticed that when on the plane it leans a little left.
I can level it with the trim but I end up with about half trim on the starboard motor and barely a tap on the left motor trim button for the boat to run level>
I know the passenger seat and fishbox is mounted about 100mmm further away from the centreline of the boat than my seat is on my side and the batteries are also down the back in the port transom box.

I have tried to offset this with the 120ltr esky, ice, bait etc in the rear starboard corner and Ive also filled up the 40 ltr bait tank sitting on the starboard transom but the boat still needs more starboard trim that port to level the boat.

I was wondering if this is an effect of the twin motors and prop torque?
I have also noticed that the plastic directional fin thing on both outboards are significantly swung to the starboard side?

Any thoughts re causes or remedies?

cheers

[Mopheus]

Prop torque from a standard CW outboard will lean a boat to port. Are you running 2x CW motors or CW + CCW? Sounds like 2x CW from how you say the torque tabs are adjusted, so double the prop torque effect.

Torque tab to starboard is correct for CW props. Prop torque is trying to walk the back of the skeg towards starboard causing a turn to starboard. Flow of water past a starboard-adjusted torque tab tries to move the back of the skeg towards port, counteracting the prop torque. That only addresses directionality issues though and not the overall torque lean effect.

I've heard that RIBs are prone to it (big motors; not much hull contact on plane) and they sometimes offset the outboards to starboard slightly (25-35mm) to help balance things out. Not an option for your boat but just confirmation that torque effect can be significant.

[Noelm]

It's normal for a cat to not have the motors trimmed the same, in fact, you will use this when trimming for different seas. Have you tried moving the tabs on the motor? just move them a bit at a time, and remember they steer the motor, not the boat, so you need to think about which way to adjust them.

[scottar]

Large transom mount transducers can also have some effect.

[Lovey80]

My old 5.2KC would be lighter than your sailfish I had my little tabs straight and never noticed a bias to the left. Both same rotation of the props. Sea state was the biggest factor it which side got trimmed up more.

are you 100% you don’t have water in one section of the port hull?

[Tracker]

does it sit level when stationary?

[Brettoh]

It's normal for a cat to not have the motors trimmed the same, in fact, you will use this when trimming for different seas. Have you tried moving the tabs on the motor? just move them a bit at a time, and remember they steer the motor, not the boat, so you need to think about which way to adjust them.


Hi mate, yes agreed and Im getting good at inducing a lean one way or the other to soften to ride or to avoid digging in however even on dead flat water and no wind I have to trim the starboard motor up about halfway on the digital gauge to level the boat from the perspective of the helm seat.

No I havent moved those tabs yet and I know they are there to aid or reduce steering effort but I did wonder if the angle they were at was pushing the rear of the boat to the left causing the lean. I might have a play

[Brettoh]

does it sit level when stationary?

not quite and I guess that is to be expected given the batteries are on one side (port) and the passenger seating adn fishboxes under the passenger seat are set closer to the gunwhale on the left than the boxes under my seat are positioned to the right . I have positioned a heavy esky at the rad starboard side to make the boat sit level at rest but that doesnt seem to solve the slight lean to the left when undersay.

The lean is probably visually worse than it is because of the design pf the bow rail which runs across the front of the boat. Its a great leveller with the horizon as a reference.

[Brettoh]

Large transom mount transducers can also have some effect.

I have a P66, livebait skimmer tube and pump on that side and a 3 in 1 simrad , bait skimmer and pump on the other side too.

[Brettoh]

My old 5.2KC would be lighter than your sailfish I had my little tabs straight and never noticed a bias to the left. Both same rotation of the props. Sea state was the biggest factor it which side got trimmed up more.

are you 100% you don’t have water in one section of the port hull?


I am pretty certain there is no water in the hulls. I drain them on the ramp after each outing and I do not believe there are any individually sealed chambers in there. I wind the front up quite high to get any water out of the hulls and even wick out the stuff that cant escape via the bung holes.
I might experiment with the tabs and straighten them up a little

[Brettoh]

I have been reading that 4 blade props generate less prop torque. I wonder if this is something to consider?

[scottar]

I have been reading that 4 blade props generate less prop torque. I wonder if this is something to consider?

Have heard similar. A recent post on facebook from a bloke down south who does vessel propping and set up sorted a lean on a Victory with a 4 blade. Downside is that the other thing they produce is a heap less bite in reverse - plenty of froth and bubble but a lot less thrust. I assume you have had a good look at the hulls with a straight edge to rule out a hook?

[gazza2006au]

Just a thought but are both engines tracking equilly rogether and are the engines squared to the length of the hull just thinking if one engine is slightly turned maybe 10mm and the other engine is perfectly straight it may cause one engine to dig down due to water force

[Lovey80]

I am pretty certain there is no water in the hulls. I drain them on the ramp after each outing and I do not believe there are any individually sealed chambers in there. I wind the front up quite high to get any water out of the hulls and even wick out the stuff that cant escape via the bung holes.
I might experiment with the tabs and straighten them up a little

When you shine a light up the bung holes. How far up the hull can you see?

[catshark]

when i owned a cat , the steering was great until i screwed up the seals by adding red instead of clear fluid , any way after dealer fixed it it didnt track right , hard to trim and just wasnt the same , i dont know what they changed but imagine my embarressment when i didnt no this until i took a buyer out shorty after to test drive , in saying that its least likely the cause , none the less something to consider

[Brettoh]

When you shine a light up the bung holes. How far up the hull can you see?
HAvent looked but I have held the water hose on jet and was able to hear the water hit something a fair way in.

[Brettoh]

Have heard similar. A recent post on facebook from a bloke down south who does vessel propping and set up sorted a lean on a Victory with a 4 blade. Downside is that the other thing they produce is a heap less bite in reverse - plenty of froth and bubble but a lot less thrust. I assume you have had a good look at the hulls with a straight edge to rule out a hook?

No I havent checked with a straightedge.

Interesting re the props

[Noelm]

My advice, try the little trim fins first, then put tape over the trim gauges and don't look back, enjoy your boating.

[Brettoh]

Well , I went for a solo run on Wednesday and the boat was level which leads me to think the previous owner set everything up for solo.
Im going to move the batteries so that one is each side of the tunnel instead of both on the one side. Then Ill work around with live bait tank water and and the esky and see what happenss.
Thanks for all of your help everyone.

Cheers