Was Told I Need Bigger Rudders

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AusCan said:
I just had a look at some pics of "Bluewater" boats. You're not wrong BP. They may need more than twins to be nimble when docking even if they had larger rudders. Maybe a good candidate for a big set of thrusters.
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Any thruster, bow or stern would have to be of the "appendage" type. There is not enough hull to put in a tube.
 
Rudder does have effect turning a twin engine boat. Test it by rotating the boat with one engine fwd and the other in reverse. Repeat with rudders fully turned in the direction of the turn. On my boat at least, it makes for a noticeably quicker much tighter turn.
 
Since Mr. Firefly seems to be MIA I wall comment that my lady thinks I need a bigger rudder. Apparently, smaller high speed rudders are not adequate for longer slower cruises.
 
Hi,

Ruder makes bigger and more efficient can also be the risk of boat losing stability in some situations big surfing. Here the pilot vessel went this way and people died, too effective for the ruder and at the same time wave beats and rotates the excess ruder turned the boat up to the bottom ...

Learn from this, make more moderate moves ruder if crosses a big sharp wave.
 
Then of course pulling in bow first does solve a bunch of problems in tight slips.
 
boatpoker said:
it seems to have been overlooked that the op's boat is a lightly built, shallow draft vessel with extremely high windage and no keel. Sometimes you can't get there from here.[/qu!!!!!!

THANKS !!!!
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Considering the configuration of your boat with shallow draft and a lot of windage I'd consider a bow thruster. Bigger rudders would help some and flanking rudders would help more but they might cost as much or more than a thruster. There's also stern thrusters that kick up out of the way when not needed.
 
Fish53 said:
Considering the configuration of your boat with shallow draft and a lot of windage I'd consider a bow thruster. Bigger rudders would help some and flanking rudders would help more but they might cost as much or more than a thruster. There's also stern thrusters that kick up out of the way when not needed.
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These boats are very lightly built, their hulls and structure are simply not strong enough for bigger or flanking rudders. The cost to make them so would be extreme. When lifting in a travel lift one can see the hull distort significantly unless spreaders are used. As one previous poster put it, think wide, flat, shallow houseboat hull.
 
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It would appear that some boat handling practice might be in order then?
 
The rudders on my boat are good size for slow maneuvers, and usually I leave them centered and use the twin props, but that turns out to be the easy stuff. When you want (or need) to do something a little more sophisticated, rudders do matter. If your rudders are *actually* undersized and metal, they can be enlarged easily by someone who knows what they're doing. If fiberglass then its a different situation.

Ken
 
It seems to me that the OP has a boat design that is all windage, with very little keel surface to provide the force of lateral resistance.
 
kartracer said:
On my 45 ft Bluewater Coastal Cruiser I was told that I have high speed rudders and that's why it is hard to dock or control at low speed. Is there a way to add on to the rudders to get a larger surface or due I have to buy new rudders.
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We have a 51 ft Bleu water Coastal cruiser and the rudders work great. BUT for docking I leave the rudders centered and only work with the engines.
Leaving the engines at tick over ( just stationary ) and put them in and out of gear to maneuver

simple

at slow speeds rudders do NOT work well so forget about new or bigger rudders
 
I owned a Bluewater 45 years ago. It had a pair of 330 HP freshwater cooled gasoline engines. Nice big props that could throw a lot of water when needed. The rudders were small. It is a planing hull, light for its size. Lots of wimdage and floated like a leaf. Any wind would make it a handful on slow speed maneuvering. But with a little practice working the throttles and gears I could turn her in her own length, back into any slip that was wider than the beam and stop her on a dime. Forget about the rudders. You have a very maneuverable vessel. Learn to use the props to control her.
 
kartracer said:
On my 45 ft Bluewater Coastal Cruiser I was told that I have high speed rudders and that's why it is hard to dock or control at low speed. Is there a way to add on to the rudders to get a larger surface or due I have to buy new rudders.
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What do you mean by "low speed?" If you're talking about when you come down from your cruising speed of 15+ knots to around 2-4 knots, then perhaps you do need larger rudders to help steer when you turn the wheel - although you could easily steer with the engines and the rudders mid-ship.

Docking is another matter altogether. As some have suggested, you can use your rudders to some effect when docking, but of greater effect is the use of your engines, port/starboard and forward/reverse. If you haven't learned how to use your engines (at low rpms) to twist your boat around and use the prop-walk to your advantage, perhaps you need to read a few books and practice, practice, practice!
 
I can't find a reference for the 45ft Bluewater Coastal, only the 43' and 47' which appear to be single engine gas powered.

On a slightly related subject I have a Leopard 47' PowerCat. At five knots or less you tighten the friction lock on the wheel so you won't be tempted to use it and steer with differential power. However, I am interested in rudder extensions for long-range cruising on one engine. The crews who deliver these boats all over the world from the factory in Cape Town, South Africa use this technique with extended rudders and then swap them out for stock rudders after delivery. This substantially extends the range of these boats. The extended rudders better mitigate the effects of the asymmetric thrust during single engine operation.
 
Do lLeopard power cats have saildrives where the rudders are in front of the saildrive like the sailing version?
 
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ProMaritime said:
I can't find a reference for the 45ft Bluewater Coastal, only the 43' and 47' which appear to be single engine gas powered.

On a slightly related subject I have a Leopard 47' PowerCat. At five knots or less you tighten the friction lock on the wheel so you won't be tempted to use it and steer with differential power. However, I am interested in rudder extensions for long-range cruising on one engine. The crews who deliver these boats all over the world from the factory in Cape Town, South Africa use this technique with extended rudders and then swap them out for stock rudders after delivery. This substantially extends the range of these boats. The extended rudders better mitigate the effects of the asymmetric thrust during single engine operation.
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I found a dozen of them like this one in five seconds. Don't know what you are looking at but the subject vessels regardless of size are twin gassers.
 
I would love bigger rudders. They are so lethargic even at my 8.5 it cruising speed. I would definitely like larger rudders someday.

When docking, idling the engines and using forward and reverse only isn’t enough. I often have to use at least 1000 RPM in both forward and reverse to really make anything happen or to overcome any kind of wind. I do bring the engine to idle before shifting, then bring the rpm back up again if need be.

I’ve been told 1200 rpm is safe in reverse. Is it the prop or the transmission that doesn’t like much rpm in reverse?
 
kartracer said:
On my 45 ft Bluewater Coastal Cruiser I was told that I have high speed rudders and that's why it is hard to dock or control at low speed. Is there a way to add on to the rudders to get a larger surface or due I have to buy new rudders.
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All conglusions are correct if you have twin engine&twin rudder.Ex.owner of my boat adviced also using engines at idle only while docking/maneuvring But If you would like to change the rudder dimensions please check the existings first.
As thumb of rule;

Rudder height : Should be 2/3 of draught,

Rudder lenght :Should be 2/3 of rudder height ,up to 15 Knots speeds.

Than you can reduce each rudder area by 20% if boat has twin rudders.

This is old DNV standarts for fishing trawlers.
 
Imported several Taiwan yachts in the late 70's and early 80's including a lot of Monk 36's from the MMC yard. All had small rudders. Easy fix, went next door to a lumber yard, bought a length of 2 x 4 and had them cut it diagonally. Sealed with thinned epoxy and bolted and bedded to the aft rudder edge - problem solved.
 
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On slow single screw boats you can put rudder cheeks of both sides of the rudder. It is about 15 degrees . On a tug a owner consult with a N/A and he will tell you the proper size. When I ran the TEXACO Sky Chief it had that and we called it a Barn Door Rudder. Should you do that do not put the rudder hard over at full speed. Note the tug has cheeks on the rear. The cheeks are a wedge that gives the vessel more rudder power.
 

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Another method is to "box" the rudder in by adding side plates to each side on standoff plates. This gives more thrust and control, almost a Kort Nozzle effect. Here is a pic of how I did that to one of my RC tugs.
 

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McGillicuddy said:
Well, I hate to throw a bucket of cold water on those who say you don’t need rudders to dock a twin screw boat but I would disagree. Use of rudders while docking greatly enhances the bag of tricks at hand for variable conditions including high current, breezy days and tight spaces. You will need rudders to walk a boat sideways into a berth. If you don’t know how to do this, have someone show you how, it will certainly enhance your boat handling skills. Although I have a bow thruster, I seldom find use for it as I use my rudders in conjunction with engines to get into tight spots. Oh and btw I consider my rather small rudders to be a detriment and would rather have larger but they work well enough for me to single hand my 53’, 62,000lb boat into most berths.
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"Diddo"

My NP45 has a keel and some weight (40,000 lbs) and a huge rudder which, makes docking so much easier.

My Carver C34's rudder was worthless below 5 knots but when used properly with the twin screws and thrusters the boat was dockable but rarely easy. With no keel the wind would take that boat and make life miserable. Even with the thrusters. It was a light boat at 18,000 lbs and had a tonne of windage. It was always a white knuckle docking fiasco with the constant afternoon winds on the San Francisco Bay.

Get a bow thruster and have a captain work with you for a day.

You will get it.
 
If one has two engines, why would one need large rudders in low-speed situations? Assuming one knows how to operate twin engines for maneuverability.
 
markpierce said:
If one has two engines, why would one need large rudders in low-speed situations? Assuming one knows how to operate twin engines for maneuverability.
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Small rudders don’t do much at low revs. The advantage of large rudders is they are of some use at even when in nuetral. With two engines and small rudders, bursts of power are required to manoeuvre. This takes time to perfect.
 
I guess the difinition of small and too small needs a bit more defining.

To me, too small is where bursts of power are always needed versus just occasionally or in extreme conditions/manuevering. But that probably is not how everyone sees it.
 
When in idle (3kts) I have very little control with the rudders. This makes maneuvering in tight marinas more stressful than I feel it should be.

My old marina was tight. I feel like riddlers should be able to control the boat in idle. For me the most part they do, but I would often have to use two full turns on the wheel to make a slight correction. And even still I’d have to use power or transmission to help.
 
Here’s the pic
 

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Steve91T said:
When in idle (3kts) I have very little control with the rudders. This makes maneuvering in tight marinas more stressful than I feel it should be.

My old marina was tight. I feel like riddlers should be able to control the boat in idle. For me the most part they do, but I would often have to use two full turns on the wheel to make a slight correction. And even still I’d have to use power or transmission to help.
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That's not all that atypical at speeds of 3 knots or so, especially if there is any wind or current.

In tight areas, most move to throttles and shifters rather than rudder. Many diesel boats with decent rudders have such high idle speeds in tight areas, they are in neutral on one engine, and alternate to go straight.

And that last picture doesn't even look all that tight.
 
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