Rudders too small?

O

Oscarlyy

Member
Aug 25, 2015
65
Canada
Boat Info
1989 345 Sedan Bridge
Engines
1989, rebuilt Mercruiser 454, 100 hours
Hi CSR,

I have a fairly rare boat, a 1989 SeaRay 340/345 sedan bridge with strait shafts in prop pockets. I have a real problem with keeping the boat going strait even if there is no wind. I have a top of the line ComNav autopilot and even it has a hard time keeping going in a strait line. The boat just reacts so slowly and only starts reacting quickly at about 8 knots which is a very bad speed for me fuel wise. I'm guessing bigger rudders for the boat would make it respond a lot better but I know it won't be as good as a boat without prop pockets. What are my options for this? And does anybody know a bigger rudder that would fit my boat from another boat? Thanks guys! I know whatever I do with the rudders won't be cheap!
 
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Thats one thing I've noticed about these Sea Ray boats is they put way too small controls on them. I have a 87 268 SD that I bought this past winter and the previous owner said it was a dog getting on and staying on plane, then I noticed that Sea Ray only puts on 12" trim tabs???? on a 27' boat really! one of the first jobs I did was put the proper 27" tabs on. So I would guess that Sea Ray did the same with your rudders and cheaped out on the size needed, I guess they didnt read the Titanic's accident report:huh: lol. Could you not get a local welder to add on more surface area to your existing rudders instead of replacing the whole unit?

Scott
 
On my 39 ec they added a plate 10"x 14" to my rudders and i have pockets as well and it does handle good at slow speed.
 
eagleone said:
On my 39 ec they added a plate 10"x 14" to my rudders and i have pockets as well and it does handle good at slow speed.
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How much did that cost you? Did you have to remove the rudders?
 
Ottawamerc said:
Thats one thing I've noticed about these Sea Ray boats is they put way too small controls on them. I have a 87 268 SD that I bought this past winter and the previous owner said it was a dog getting on and staying on plane, then I noticed that Sea Ray only puts on 12" trim tabs???? on a 27' boat really! one of the first jobs I did was put the proper 27" tabs on. So I would guess that Sea Ray did the same with your rudders and cheaped out on the size needed, I guess they didnt read the Titanic's accident report:huh: lol. Could you not get a local welder to add on more surface area to your existing rudders instead of replacing the whole unit?

Scott
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I will look for a local welder to make them larger. I think I need to upgrade my tabs as well but they are only single rams
.
 
Have no idea of the cost because a different owner had it done, but yes you will have to take them off to get a good job.
 
My previous boat was a '89 300 Weekender w/twin 454's. I was involved in an accident with an underwater obstruction, damaging both rudders. The boatyard thought the stock rudders were too small so they had new ones cast that were bigger. At idle there was no problem, but once up on step... OMG, it was a nightmare. I ran the boat back in immediately and they cut them back down to stock size.
 
The Bill Collector said:
My previous boat was a '89 300 Weekender w/twin 454's. I was involved in an accident with an underwater obstruction, damaging both rudders. The boatyard thought the stock rudders were too small so they had not ew ones cast that were bigger. At idle there was no problem, but once up on step... OMG, it was a nightmare. I ran the boat back in immediately and they cut them back down to stock size.
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interesting. Please elaborate.
 
dpmulvey said:
interesting. Please elaborate.
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It was extremely difficult to keep the wheel in your hands as all of that thrust from props inches away now catching these oversized rudders. I was fighting a monster just to trying to go straight... If you let go of the wheel it was very hard over, not good on step.
 
The Bill Collector said:
It was extremely difficult to keep the wheel in your hands as all of that thrust from props inches away now catching these oversized rudders. I was fighting a monster just to trying to go straight... If you let go of the wheel it was very hard over, not good on step.
Click to expand...

That is interesting. I wouldn't think that they would have cast a replacement which moved the rudder closer to the prop. That would mean material being added before the rudder pivot point which would really cause a high speed handling issue. I would think a slightly longer in height and trailing width would work better.

That said....you get used to the small rudders.....and rely on the transmissions at slow speed to steer the boat.
 
Makes sense if I am visualizing it correctly as I believe PlayDate is. That would be a nightmare. Your pivot point is closer to the center of the rudder as opposed to the leading edge.
 
Have you checked the fluid? If it is low the rudders don't respond well especially to slow small inputs.
 
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