Help, Why does my boat heel over at speed?

[Flames]

I am new to this forum so I'm hoping somebody can help me with a problem I have with my 36ft Sealine flybridge.
About 5 weeks ago my boat ran level and even at 3200rpm when on the plane. It then came out of the water to have new steering bushes fitted in both drives whilst the work was being done the engineer fitted a new cone clutch and spacer and split locking ring to the port leg.
After fitting new top and bottom seals, anodes, gear linkage cables and anti fouling the hull it went back into the water last week.
On testing at speed I found that the boat heeled over to starboard about 30 degrees down angle when getting up onto the plane. The water conditions was good with no real wind. I ran the boat both north and south over a 2 mile distance with the same results both ways. Strangely the trim tabs made no differance they wouldnt raise the starboard side. the only way I could get the boat to run level was to have one leg at -4 and the other at +4.
Now I know its not the tabs, I can see both working and they were tested out of the water.
I know its not the fuel as both gauges show even and the levels are the same as 5 weeks ago.
I know its not the water tank. I know its not the holding tank even though its fitted on the starboard side it is without doubt empty.
Both engines, Ad41s, appear to run the same with the turbos whistling.
The propellers are Volvo A6s and are in good condition. I can see through the water all 4 are there with the locking cones in place.
I am beginning to run out of ideas where to look next. So if anyone has experienced similar problems or if there is somebody with engineering expertise I would be most grateful for any advice.
Many thanks Dave.

 

[spannerman]

It sounds like one of the trim senders isn't calibrated properly and the drive the engineer stripped needs resetting. I am sure the boat is fine and when you are running at +4 and -4 the drives are actually at the same angle of trim, but if you run the drives at the same 'indicated' trim angle then one drive is way out compared to the other.
They should both read around -5 when fully down, we always set them so that at zero trim the cavitation plates are parallel with the bottom of the hull.
You might be able to see over the swim platform if someone runs the trim and you watch the drives move while they call out the readings.

 

[Nick_H]

If it's not listing heavily at rest, then it can only be trim tabs or drive trim, or some appendage hanging off one side of the boat below the waterline. You'd easily spot the latter, so its a trim problem, most likely the issue Spannerman mentions.

Alternatively (and i'm no expert on trim tabs), could it be a leaking valve or seal on one of the trim tabs so one tab stays down and the other doesn't. They would still appear to operate normally at rest, as there would be no load on them

 

[DavidJ]

When both drives are fully down, resting on the stops what's the reading? Incidentally I always leave mine in this position to prevent barnacles sticking to the working part of the ram.

 

[Flames]

Many thanks for the replys so far.
The one bit of information that I forgot to add into the original story is that I was with the engineer when he set up the drive trim settings.
Both drives had new racks fitted to the steering helmets so I know that they were set at -4 when fully retracted into the boat. They were also fully tested in and out of the water and appear to operate as designed from -4 to +46.
I normally run around at low speed with the legs in the -4 setting. Indeed prior to and still now the boat gets up onto the plane with the legs on this setting with the trim tabs up.
It also seems unlikly to be trim tab fault as both are in the raised position with the rams fully retracted.
I did actually think at first that I must have the port trim tab stuck in the down position causing the boat to heel over to starboard but this also is not the case as both work correctly and are retracted.
I am still at a loss to see what could be causing this problem. Is it possible that that the port leg is not on properly? Is it possible the drive is not straight and is trying to turn the boat to starboard and heeling it over? I ask this because if I steer to port then the boat levels up but obviously starts to head to port also.
Could I still have a problem with the clutches? Would changing only the one cause it to be more powerful than the other at similar revs?
Thankyou once again for your advice. Dave.

 

[Nick_H]

That's certainly an odd one, but I still think it can only be trim, either the tabs or the drives. Do you have a friend/neighbour who can run their boat behind yours to see what's happening when you're on the plane? The tabs and drives will be visible from the back when you're on the plane, so it may give you a clue as to where the problem is.

 

[benjenbav]

Could it be as simple as the polarity is back to front on one of the trim switches so that when both guages read -4 one leg is up and the other is down?

 

[volvopaul]

Sounds like a trim/drive angle issue as to carry out the bush removal and refit the sender potentiometers have to be removed then set up from scratch after the drives have been fitted to the boat.

Did you trim the drives right in prior to fitting the racks and setting the finer adjustment on the pot sensor?, is the engineer a volvo man as he should have made a visual inspection of the drives after removal of so many parts after setting up the trim gauges to read correctly.

Also he would have removed the steering arms from the steering helmet, there are various points where the steering link arm can be re attatched maybe he has placed the link pin in the wrong hole which would alter the toe in/out slightly.

What I would do next run out is trim both drives in until you can hear the trim pumps blow off the valves, get the boat on the plane, make sure the tabs are up and then play with the trim angle without looking at the gauges till you feel its ok, then make a check on where the gauges read, it seems very strange you req one at -4 and the other a plus 4 to make it right.

 

[lenseman]

Many thanks for the replys so far.
The one bit of information that I forgot to add into the original story is that I was with the engineer when he set up the drive trim settings. . . .

Hello Dave

As you know the engineer, get him back and take him out in the boat and get it on the plane. 30° is very noticeable and he will soon put it right for you.

Let us know how you get on?

 

[Red]

Hi,

Some boats have a tendency to lean into the wind - quite pronounce and noticeable on a relatively calm sea.

Have you check that someone has not stolen one of the engines, this would cause a list....

 

[neale]

Hi,

Some boats have a tendency to lean into the wind - quite pronounce and noticeable on a relatively calm sea.

Have you check that someone has not stolen one of the engines, this would cause a list....

Flybridge's with outdrive would be particularly susceptible to this but the OP said they ran in opposite directions and the lean was to the same side. If it was wind induced the lean would have transferred sides.

I am guessing the OP has a F33 or F34. The F36 is on shafts.

 

[Flames]

Thanks all once again for the replys.
I have just arranged to meet the engineer this weekend so we can test the boat on the plane together. I must say he also seems a little mistified as to why this is occuring. Even though I have used him exclusively over the the past few years I dont believe he is an "official" Volvo man.
With regard to Reds suggestion, I will check that both engines are there, I'm fairly sure I would have noticed the gap when I last looked, but you never know!
With reference to Volvo Pauls reply I'm very intrested in reading about the steering link arm connections. I dont know why but I feel the issue is somewhere in that direction. I was there when he set up the drive potentiometers. I know the drives were fully in and then the settings were done and checked in all positions.
If the toe in, toe out angle was not as it should be is it likely that could be an issue?
Also could Volvo Paul, Spannerman or someone else tell me is it possible for the cone type clutches to be able to slip when under 3200 revs of torque thus producing less thrust on one set of props?
When the boat was tested I did trim the boat using the drives without looking at the gauges thats where the -4 +4 settings came from. Unfortunately at that point the water was to murky to actually see quite where the drives were positioned.
I would love to have some idea of what could be wrong before testing the boat again on Saturday. I'm sure at some point the cause will be located and put right, I just hope it dosn't take forever.
I suppose on the positive side, as I have not yet paid for the work the ball is maybe just about in my court!
Many thanks for your replys Dave.

 

[spannerman]

As those of us who have been in the business for a few years know, 'anything is possible', but I would think it improbable that a cone would slip at 3200rpm as they would be under load and its the resistance in the drive system that makes then lock up and work. They normally slip at low rpm when going into gear and increasing the revs slightly will get them to bite and lock up.
But you could have a prop hub that is slipping, as once they have slipped once they will do it every time when they get to a sufficient load, so that the rubber insert slips in the hub.

 

[Flames]

Sorted at last, what a relief.
I met with the engineer on Saturday morning and we took the boat out on test again with the same result. When getting up onto the plane it heeled over to the starboard side.
He checked all the settings again from inside the engine bay steering arms, leg angle, reservoir levels etc with no joy so we decided to lift the boat out to check the drives and tabs.
On lifting it immediately became apparent what the problem was-
The bow thruster had sucked in a 6 ft length of plastic bag, the type that carpets are wrapped in.
The boat was dragging along its starboard side a 5ft water filled sausage. It was only when we went to get it out that I became aware that the sheer pin in the thruster had broken saving it from even more damage.
With the sausage removed the boats straight up on the plane running level and even at last.
I suppose in hind sight I probably should have noticed that the speed must have been down with the extra drag. Also if I had of been anywhere other than the east coast, then with clearer water maybe I would have seen the problem right away.
Still after the "very reasonable" cost of a lift out and a new sheer pin I'm now a happy boater again.
Many thanks to all that have read this sorry story. Dave.

 

[benjenbav]

Excellent. Glad it's sorted. But what a sight it must have been if you'd been able to see it.

 

[stelican]

Sorted at last, what a relief.
I met with the engineer on Saturday morning and we took the boat out on test again with the same result. When getting up onto the plane it heeled over to the starboard side.
He checked all the settings again from inside the engine bay steering arms, leg angle, reservoir levels etc with no joy so we decided to lift the boat out to check the drives and tabs.
On lifting it immediately became apparent what the problem was-
The bow thruster had sucked in a 6 ft length of plastic bag, the type that carpets are wrapped in.
The boat was dragging along its starboard side a 5ft water filled sausage. It was only when we went to get it out that I became aware that the sheer pin in the thruster had broken saving it from even more damage.
With the sausage removed the boats straight up on the plane running level and even at last.
I suppose in hind sight I probably should have noticed that the speed must have been down with the extra drag. Also if I had of been anywhere other than the east coast, then with clearer water maybe I would have seen the problem right away.
Still after the "very reasonable" cost of a lift out and a new sheer pin I'm now a happy boater again.
Many thanks to all that have read this sorry story. Dave.

Thought that was the problem

 

[No Regrets]

If it's not listing heavily at rest, then it can only be trim tabs or drive trim, or some appendage hanging off one side of the boat below the waterline. You'd easily spot the latter, so its a trim problem, most likely the issue Spannerman mentions.

Alternatively (and i'm no expert on trim tabs), could it be a leaking valve or seal on one of the trim tabs so one tab stays down and the other doesn't. They would still appear to operate normally at rest, as there would be no load on them

Good call!