Torque roll
 

2006 Sunsation 288 MCOB. Sometimes while cruising out of nowhere the starboard side is damn near at water level. But oddly it’s not all the time and can’t figure out why. Yesterday I was running a 4blade bravo 1FS and it was bad. I’ve ran a 5 blade also and it does it also. If I drag the starboard tab I can level it out. Is there any way to make it go away or not be as bad. I just ordered a new 5 blade prop yesterday after begging several componies to sell me a prop. It’s impossible to get in touch with them so figured I’d ask here first. wondering if prop choice can maybe help or maybe drive height or something. Current drive height is 3” prop to pad. Bravo XR with ITS. Prop I ordered is a herring 5 blade 27 pitch 15.5 diameter 22 rake.

FJ propeller in Ft Lauderdale has always answered the phone anytime I have called. They do great work there and have other locations as well including one at LOTO and I believe they own Hering now as well.

Thanks, I bought direct from Herring. I’m going to call back and discuss with him because it was one of the things on my list to ask about but I forgot. It’s 3-4 months out so I’m sure I have plenty of time to adjust. Reading other posts I’m thinking the recommendation is going to be to stay away from a 5 blade but it’s not any worse with a 5 than a 4.

Dagwell,

What's your drive ratio? Any slop in the gimbal?

I can't imagine Sunsation would have sold a boat that listed that bad. Stock power? I ask about drive ratio because prop pitch is the major contributing factor for torque roll. You could maybe drop pitch and increase drive ratio and reduce torque roll. We go about it differently, being direct drive, but we can often reduce prop walk in our model boats by reducing pitch and running the engine in a higher RPM range.

Thanks. Brad.
(937)545-8991

I do NOT know if this is the answer to your issue, but it may be an option.

https://www.boatzincs.com/mercruiser-zinc

Attachment 577451

If you scroll down through the zincs that mount to the cavitation plate, above/behind the prop, you will notice that they have options for different ones that a fin to them. I have seen those installed slightly off from directly aligned with the drive, in an angle that will counter the prop torque.
Again, you will need to talk to an expert to see if this is something you can/should try.

Have you talked with the folks at Sunsation? That would be my first call.

Padraig

It would be interesting to understand how some Super V class racers are turning 6 blade Herrings and a 1.5gr without a problem. I like the idea of spreading the load to 6 blades and it has been described to me as "smooth as butter".

Okay, thought i remembered a different drivability thread by the op. See this;
https://www.offshoreonly.com/forums/...-slipping.html

So, between the two threads, something is substantially off with this boat. Design ? Propping ? Rigging ? Mounting ? Driver ?

Only boats i’ve been in that rolled to one side that much, where bow steering. Interested to see what ultimate cause of these issues are for the OP and this boat.

so as for that last post I ordered a new prop and have tested a 5 blade and concluded there is nothing wrong with the boat it was a prop issue. Maybe it’s bow steer and not torque roll. Boat has no issues when getting on plane or at wide open throttle sits flat. But at lower cruising speeds sometimes it just happens. I’m new to boating and maybe it’s operator error 🤷‍♂️ But I’d low to know what I’m doing wrong.

thanks maybe that will help. I’ll look into it.

ratio 1.5 stock power 525 efi. Not sure on the humble slop but will look into that. Is there a certain way to check that other than shake the drive for any movement? The new prop is a lower pitch. So maybe that will help. Guess we will see.

I have not. But I guess that’s a good place to try.

https://cimg7.ibsrv.net/gimg/www.off...de1f57e4e.jpeg
So, I was reading these reply’s and just thought about something. There is a repair on the (not sure it’s real name) plate below the prop. And it sticks out about a 1/4” more on the starboard side. Could that be my problem? If so maybe I’ll just grind down the weld and try that.

its called a skeg and I would remove it

Dagwood,

I cannot imagine it not having an effect.

If you do grind it down, and the torque roll is still there, I'd be more inclined to follow SB's train of thought. Seeing as you're new to boating, it might be fair to consider operator error. There is more to driving a boat than throttle and steering. With both boats I've owned, I would set the drive trim all the way down for take-off, which helps to get it on plane quicker with less bow rise, then trim it up to achieve proper ride attitude. When I trim up after planing, I can actually feel the boat free up. What happens is the bow lifts a bit, which gets more of the boat out of the water, allowing for less wetted surface. The "bow steering" that SB mentions comes from the bow being pushed down into the oncoming water. When you take off, do follow a similar process, or leave it where it is, wherever that may be?

Try and have a friend take a pic or video of your boat on plane from the side. This will tell us a lot about how the boat rides, as far as attitude.

Further.... When you grind that weld bead away, do you best to keep the trailing edge as sharp as you can, but minimal rounding. The sharper the trailing edge, the more efficient the movement through the water, due to the Bernoulli effect. Don't leave it so sharp it will cut skin, but don't round it off, either.

And, for the record.... That boat should run pretty well with that 28P Bravo1 prop. I get ~76MPH out of my PQ280 with one. And no torque roll.

Thanks. Brad.
(937)545-8991

Dagwell,

Remove the weld bead. Not the skeg. :angry-smiley-038:

Thanks. Brad.
(937)545-8991

The two owners are brothers and super intimately hands on with their boats. They used to give out great advice to sunsation owners on the forums, before the forums died iff substantially. Be really smart to givem a ring.

thanks, it runs 75 now on rev limiter hoping for high 70s maybe 80 with the new prop.

lol, will do

Maybe it's just the picture but is sure looks like the skeg is significantly bent to the side and someone has attached something to the trailing edge of it that should not be there.

it’s not bent, but that back inch starts to taper out a bit like someone welded a strip of aluminum on and the back of the skeg is much thicker and sticks out way more on the starboard side. That pic was a pic i
happened to have I’ll send another when I pull it out of the water tomorrow or Saturday. I noticed it when I bought the boat but the welds looked solid and didn’t concern me until I was thinking about what could
be causing this issue and thought of that.

Looks like some one welded a torque tab on. Who knows why. That’s mostly the cause or at least part of the cause of your issue

I just looked up what a torque tab is and that is def what it is. I’m gunna have to ask the shop that always maintained the boat and see if they installed it for the old owner and why.

Wonder if that is giving you your slip issues too.

I have never seen one on an outdrive, so i have no clue why it’s there .

Talk to the people who did this to your boat 1st. See what their reason was.

At this point I’m nervous to grind it off. Maybe it’s correcting another issue that I’ll create if I take it off? 🤷‍♂️ Is it possible it came with that on from factory? Guess I’ll have to ask the shop and maybe ask Sunsation also.

Cut that skeg off and get a normal one welded on before buying more props.

2006 has the new bottom.

Did some work Years ago on a 28 but it was a 2001 or so, no odd issues like that. It had issues with staying on the pad when it had the power to get on it but nothing crazy like what you are saying.

https://cimg8.ibsrv.net/gimg/www.off...fe886e03b.jpeg
Pulled it out today. Here’s some pics. Flat on port. Tapered on starboard. Fat in back.
https://cimg9.ibsrv.net/gimg/www.off...d28138d8b.jpeg
https://cimg1.ibsrv.net/gimg/www.off...3e7ccce8f.jpeg
https://cimg2.ibsrv.net/gimg/www.off...936722b72.jpeg

That repair reeks of turbulence. Water should flow past the skeg smoothly and efficiently to the prop. Hydrodynamic efficiency is key to stable and fast. Like someone suggested, I'd cut that Frankenstein off and weld a new skeg on making sure it is absolutely true to the centerline of the drive or maybe just grab an undamaged lower.
Add: That is like having a Whale Tale bolted on sideways, guess which way that will torque the boat at speed.