HEAVY STEERING ON COLVIC 26

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aldprom13

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CAN ANYBODY EXPLAIN WHY MY STEERING IS SO HEAVY UNDER POWER. THERE IS A VERY STRONG PULL TO PORT.THE ENGINE IS A YANMAR YSE12 HP AND THE PROP IS L.H. 12X11
 
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you may well find the engine is " Over-Propped" too much prop wash past the rudder.
does the engine produce much black smoke
 
I had a Colvic 26 Sailer quite a few years ago, and had exactly the same motoring pull to one side - cannot remember which way now, but had a Yanmar (single horizontal cylinder), as well.

Another Colvic 26 near mine, had a vertical strip of 1.5 x 1.5 inch wood on the starboard side of the rudder to try to help against the pull of the helm to one side.

Ours also had this same strip of wood on one side until the rudder had to be repaired when the mild steel straps from the rudder post to the in-sides of the rudder came loose. They were removed by the yard doing the repair, but never replaced.

I cannot remember if it made any difference when they were there and not there, at this time.

I do know that the easiest way to steer the boat under engine, due to the heavy pull of the tiller to one side, was to steer with the Autohelm!!

We later changed the Yanmar to a Perkins 18hp, and still had the same pull to one side - though the rotation of the prop changed. Too long ago to remember which way it then pulled.



We had the boat for about 6 years and crossed to the Channel Islands twice with her in that time - with Decca. We spent a lot of time on her in the summers. Slowish to sail but very safe.

We also had the cabin seating changed from a long stbd side seat to a 2/table/2 seating arrangement, with a shorter berth to stbd and a proper chart table to port. The boiler in the heads gave us hot water and a shower. We were very comfortable and self contained.
 
Possibly the rudder is not balanced, (i.e.,a bit of the rudder surface in front of the rudder stock), if all the rudder surface is "after the stock" it may account for the effect you describe. I had a similar boat, an IP24, I built it and it had a balanced rudder, it had no, or v little bias.

p.s. Don,t worry about some Formurites sensitivity to CAPITALS, we aren,t all so touchy! My first post, like yours produced the same plonkers. But I do oblige them now I know the FORM better. wink, wink!!!
 
The rudder is semi-balanced - but has an unusual hydrofoil section, that is very fat at the top, and less fat at the bottom. Not the same as the thin hydrofoil section seen on most boats.

The heavy helm could be caused by the proximity of the top of the prop to the hull section above. It is very close and could give a strong paddle-wheel effect.
 
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CAN ANYBODY EXPLAIN WHY MY STEERING IS SO HEAVY UNDER POWER. THERE IS A VERY STRONG PULL TO PORT.THE ENGINE IS A YANMAR YSE12 HP AND THE PROP IS L.H. 12X11

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When I had my Centaur re-engined from a Volvo MD11C to a Nanni it exhibited a fairly strong pull to port. The change involved a prop. change but I forget the prop. dimensions. My solution was to sit always to port with the tiller pushing against my right leg - a pretty effortless, hands-free, way to steer.
 
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Sounds a reasonable diagnosis Philip, maybe a smaller dia, bigger pitch prop??? Bill.

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Ahem

1/ you may well find the engine is " Over-Propped" too much prop wash past the rudder.
does the engine produce much black smoke


2/ When I had my Centaur re-engined from a Volvo MD11C to a Nanni it exhibited a fairly strong pull to port. The change involved a prop. change but I forget the prop. dimensions


we not a [--word removed--] are we
 
[ QUOTE ]
CAN ANYBODY EXPLAIN WHY MY STEERING IS SO HEAVY UNDER POWER. THERE IS A VERY STRONG PULL TO PORT.THE ENGINE IS A YANMAR YSE12 HP AND THE PROP IS L.H. 12X11

[/ QUOTE ]

On reflection, it sounds as though the rudder could in fact, be over balanced, i.e. the transverse prop wash/"walk" acting on the area ahead of the stock? Bill.
 
I have exactly the same problem which I did ask about on this forum 6 months ago.
I have only had a boat for about 4 years so I do not know too much about them and this is my first boat.
But I find it really strange that 5 boats have the same problem.
Surely this is a design fault by Colvic in that they sail well but when you use the engine we all have the same problem.
I too had the wood down the side of the rudder but removed it last season to find that is made no difference at all.
And I know before all the old hands start that Colvic made hundreds of boats but I have not heard from anyone that has a Colvic Sailor with a Yanmar 12hp engine that sails well under power.
I am really interested to find out if there is a solution to this problem.
 
I used to sail a Colvic Sailor, the bigger one than yours, junk rigged, it had no probs under power, it does sound like a design fault, resulting in the transverse wash from the prop, over the rudder creating the bias. imho, Bill.
 
thanks for the idea,I have just fitted a yanmar2gmf 18 hp and I need to fit a bigger prop so I am going to lower the shaft to suit. but what you say sounds reasonable there is only about 12mm between prop and hull which means the wash will act more on the fat part of the rudder
 
leave the shaft as is adjust via the "Pitch"
my sons Cinder 22 was "Over Propped" the most econimical way to reduce the wash past the rudder was to reduce the prop Dia by 25 m/m = problem solved.
boat doesnt "Squat" & much faster resulting in no engine overload
1 " of dia = 1 " pitch adjust prop to suit but then wtfdin /forums/images/graemlins/laugh.gif
 
Sorry Sailorman but like I said I am quite new to boats. I know this might sound silly but can you explain to me what "Squat" means when she is under power
 
When we fitted the Perkins 18, I could only use the same diameter prop without lowering the tube and shaft. I had a different gearbox fitted that made the prop turn faster without being able to go bigger. The prop had more pitch to offset the smaller diameter that it should have had.

The boat went a bit faster, and better into wind and sea under engine, but still had excessive helm when motoring.

As others have agreed, I believe it had more to do with the hydrofoil shape of the rudder, and probably prop-wash onto the leading edge of the rudder balance section - as the prop is very close to it.

You have to experience the helm of the Colvic 26, under engine, to really appreciate the heaviness of it.
 
i don't have a colvic but i've had exactly the same issue on both a halcyon 23 and a trapper 500 both of which had bigger engines than the original installed. i think the extra grunt you get is the cause with the flow over the rudder and its not being overpropped.

just a thought, on the trapper the tiller hinges up and i solved the problem by keeping the tiller low to maximise the leverage

now there's no problem. i found i was standing up when i was using the engine - usually becuase we were entering or leaving port.....
 
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