Heavy List underway

[zigzag]

Hi Folks,
I re-powered my 1988 24 offshore with a 250 Yamaha four stroke. It’s a single engine. The 200 I replaced was a right hand drive. This new 250 is a left-hand drive and the seller told me for a single Engine. It doesn’t make a difference. However, I am finding that the boat has a strong tendency to list to starboard especially while underway. I had two batteries on the starboard side in the stern and I relocated one of them to the port side. It made a little difference while sitting but underway. It’s still not right. I’m wondering if this is just a weight distribution thing or if they’re left and right hand drive is causing this. Any input would be very appreciated. since this boat is new to me, I can’t tell you whether or not this was the same way with the previous Engine.

 

[seasick]

It may not be a list per se but rather a steering to starboard imbalance.
Forst question: Does the lower unit sacrificial anode have a fin? It may not if the motor was part of a twin setup. It needs a anode with a tab.
If it has a tab, does the tab have a curve in it?
If so the tab may need to be replaced with one that has a flat (no curve) tab
The solution may be simple: The trim tab anode on the motor should be adjusted so that the trailing edge is about 15 degrees or so to port . The optimal angle depends on a few parameters, one being the boat speed. The adjustment may seem illogical but the tab does not create a turning force but rather adds drag so if your boat steer to starboard, you want to add drag to port.
Let us know what you have. Hopefully the fix is simple.

 

[zigzag]

It may not be a list per se but rather a steering to starboard imbalance.
Forst question: Does the lower unit sacrificial anode have a fin? It may not if the motor was part of a twin setup. It needs a anode with a tab.
If it has a tab, does the tab have a curve in it?
If so the tab may need to be replaced with one that has a flat (no curve) tab
The solution may be simple: The trim tab anode on the motor should be adjusted so that the trailing edge is about 15 degrees or so to port . The optimal angle depends on a few parameters, one being the boat speed. The adjustment may seem illogical but the tab does not create a turning force but rather adds drag so if your boat steer to starboard, you want to add drag to port.
Let us know what you have. Hopefully the fix is simple.

Thanks for your reply. I looked at the motor and compared it to my older two stroke 200 and noticed that it doesn’t have the trim tab on the anode it’s flat, and I asked the seller about this as well and he said that that’s just the way they make the more modern engines. It’s a 2007. But what you’re saying makes sense. I would love that to be the case because that’s a lot less expensive than changing out the lower unit! Certainly something to look into, Thanks a lot!

 

[zigzag]

Thanks for your reply. I looked at the motor and compared it to my older two stroke 200 and noticed that it doesn’t have the trim tab on the anode it’s flat, and I asked the seller about this as well and he said that that’s just the way they make the more modern engines. It’s a 2007. But what you’re saying makes sense. I would love that to be the case because that’s a lot less expensive than changing out the lower unit! Certainly something to look into, Thanks a lot!

Another thought is that the issue isn’t so much that the boat ‘steers’ to starboard, but that the whole boat ‘lists’ to starboard, so if I shift my steering position to port to balance the boat, it improves, but still lists a bit. I was thinking that I might try to relocate the other battery to port as well, but something doesn’t seem right with my setup. Would the trim tab anode make a difference in this, do you think? Or could it be the prop rotation (left vs right hand) ? Thanks.

 

[SkunkBoat]

First, if you have a set of trim tabs, raise them up and verify they are both all up.
Leave them alone while you try to troubleshoot the list.

Yes, not having a trim tab anode on a single motor can cause "list" when running because you are steering to compensate for not having the tab.
This is especially true if the motor is too far down for a given speed. Try raising the motor trim up a little more and see if that improves things.

Your motor came off a boat with twins so it did not have a tab.

 

[family affair]

What prop? If it is a 4 blade and it is mounted too low, the torque from the prop will create a list at speed.

 

[seasick]

First, if you have a set of trim tabs, raise them up and verify they are both all up.
Leave them alone while you try to troubleshoot the list.

Yes, not having a trim tab anode on a single motor can cause "list" when running because you are steering to compensate for not having the tab.
This is especially true if the motor is too far down for a given speed. Try raising the motor trim up a little more and see if that improves things.

Your motor came off a boat with twins so it did not have a tab.

Ditto on the trim tabs. Also check tabs for damage, bends, etc and correct mounting

 

[seasick]

I forgot to ask if the boat lists at the dock / when not moving. Also if the list gets worse as speed increases the issue is less likely to be weigh balance and more likely to be excessive drag/steering, of misalignment of the motor