Transom hung rudders

[skodster]

I am thinking of removing the skeg/rudder arrangement on my boat and replacing it with a transom hung item. A crack has appeared at the root of the skeg and it would be more of a hassle to get it repaired as access to the inside of the skeg is problematic.

Has anyone got a transom hung rudder on their boat? What are the advantages and disadvantages?

I know that I will have to move the sheet track forward but that's no problem. Please advise before I take the angle grinder to the fecker....

 

[sarabande]

what's the boat please ? You will need a vertical or reverse transom, and what will you do with the skeg, and present rudder ?

 

[Bobc]

Don't underestimate the loads that go through the rudder mountings. It's HUGE.

 

[Dipper]

what's the boat please ? You will need a vertical or reverse transom, and what will you do with the skeg, and present rudder ?

The Hustler 25.5 has a sloping transom and transom hung rudder although this arrangement doesn't seem very common.

Warning - don't Google 'Hustler' pictures if you are at work. You won't see many boats!

 

[lw395]

I had an Impala with a transom hung rudder.
Disadvantages:
Extra length they argue about and charge for in Marinas
Trailing edge gets rubbed by ropes when rafted.
Gudgeons prone to clonking noise on mooring or anchorage with any swell. (can be solved by good design /bushing)
Gets in the way of boarding ladder, dinghy etc.
Surface piercing foil prone to cavitation at extreme speeds...

Advantages:
Deep balanced rudder easy to do.
fittings are easily mounted to beefed up transom
Forces go straight into hull and deck, no skeg to bend
No skeg so the boat will turn fast with the stern sliding sidewise
Most effective place in terms of turning moment
Easy to clean
Can be removed with boat afloat (although a bugger to replace possibly!)
Easy to make strong enough using timber and glass or possibly foam and glass or carbon or kevlar.

Provisos
Needs a deep transom to be strong

 

[maxi]

Did the conversion on my Macwester, a great success.

Benefits: rudder easily accessible whilst afloat, steering forces moved aft by approx 10% of waterline length (less steering effort = less drag) + weather helm effect lessened, turning circle reduced.

Negatives: slight weight transfer aft. No others.

Good luck.

 

[Lakesailor]

Number of questions posed on this forum with no supporting information is extraordinary.

Are we all mind readers?

 

[alahol2]

Couple of extra points:
If you are on a fore & aft mooring, the aft bridle becomes problematical.
Ensure you design-in some decent rudder stops, you can break a rudder going in reverse if it gets square on to the direction of travel.
Make sure it is very strong; forces can be enormous.
If you design it as a vertically lifting rudder you can make it deeper than the keel.

 

[DownWest]

Lots of big boats have transom hung rudders. As said, just need to make the stock and fittings strong enough. Most difficult would be a forward sloping transom.
My 21ft build has one. PM me if you want the details of the fittings and design.

 

[Blueboatman]

Quite honestly it will be 10x the effort mess and expence to avoid repairing the Skeg . Even if this means craftily cutting out the cockpit sole or removing a prop shaft/fuel tank to do the surface grinding and overlaminating from within the hull.
Unless you fancy a transom hung rudder anyway..
Imo

 

[blackbeard]

My boat (Hunter 245) has a transom hung rudder. Some comments:

On one occasion, at low springs with the boat on a swinging drying mooring and a strong E wind, the boat settled with the rudder on a rock (well, lump of concrete). I suspect this happened a few other times when I wasn't watching. No damage apart from paint lost from underside of rudder, but that gives you some idea how strong both rudder and fittings need to be.

Boats with transom hung rudders tend to have short aft overhangs. As it is, the rudder tends to lift out of the water as the boat heels and, if it heels far enough (yes, I know, should have reefed earlier), it loses its grip on the water and the boat rounds up, out of control (unless you let some mainsheet out smartish). With a longer aft overhang, this might perhaps be more of a problem? though it is presumably related to beam as well.

Fouled rudder from stray floating lines etc is easy to clear!

Withdrawing prop shaft - to change cutless bearing, for instance - is much simplified.

 

[ProDave]

Well my boat has a transom hung rudder.

Mine sits on over sized well bushed pins so swings smoothly with no play.

I remove my rudder and store it in the cabin as we are on a drying berth, and prefer that to digging the rudder into the mud every tide. Should also mean I don't have to varnish / paint it very often either.

Main disadvantage is it forces the outboard to be offset, in my case on the Port side. But that doesn't seem to particularly effect it's performance. but I don't think the OP is using an outboard.

My biggest concern is you are changing the boat, so it may take some experimenting to find a rudder size and shape that works well.

 

[NickRobinson]

two with, one without...

My Seawych had a transom hung rudder, lived in the cabin, she she was on the mooring, shiney varnish all over- easy to steer as o/b could pivot or lock.

My Mac 26 was skeg hung, ok but heavy and poor astern. The OC tech guy told us to worry, the 40 yr old rudder tubes were scaff pole!

Sitting on my Mirage 2700 in the rain just now. Transom hung, very light to handle, and goes astern well. Autohelm copes well.

If I got charged for it as LOA, I'd have it in the cabin too

Nick

 

[boguing]

From a design point of view, transom hung has almost everything going for it.

Simplicity, possibility of lifting it, less area needed, lower water pressure if the bottom pintle rips off, less friction, easier in-water maintenance and lower overall cost.

The downside is that they will 'ventilate' more readily (but that needs to be compared to how deeply immersed the skeg hung rudder would have been at vis. heel angle). Speaking from experience, when a transom hung rudder ventilates, you just need to drop the tiller and then ease it back up. Actually true for all single rudders, but I learnt it on a transom jobby because I could see what was going on.

They are also more exposed to collision damage.

Another plus for you proposal is that you can make a far better foil section than your original had, and can have fun playing with the profile for helm feel.

And if it's not too much work, I can't speak too highly of twin rudders.

 

[skodster]

This is the project

 

[Lakesailor]

Far easier to repair the skeg.

 

[William_H]

Rudders

Yes it is probably far easier to repair the skeg. Just grind down the outside of the skin with some deep grooves across the cracks. Lay up fibre glass with epoxy to build up strength then fair the whole repair off.
You might consider using carbon fibre or Kevlar for the reinforcing, much stronger than glass but may be expensive or hard to find. Used just like glass.
However yes I am a fan of transom hung rudders. One boat that goes past here is in the 70ft class and has a suger scoop cut out for the transom hung rudder. This may help with cavitation. It also has wheel steering.
If you wanted to go transom hung rudder then you would benefit by having a top pintle extension so that the axis of pintles is vertical. Give your new rudder plenty of balance ie area forward of the pintle line. Make it as deep as possible. I would suggest you use polyurethane similar foam shaped then glassed over. Try to avoid making it too heavy.
lastly fit the bottom pintle as low as possible to minimise side loads which are as said huge. Strengthening of inside of transom would be necessary and even consider that the pintle may be torn out allowing water in to the hull. Some sort of sealing off of the area? good luck olewill

 

[sailorbaz]

Heavy rudder

Yes it is probably far easier to repair the skeg. Just grind down the outside of the skin with some deep grooves across the cracks. Lay up fibre glass with epoxy to build up strength then fair the whole repair off.
You might consider using carbon fibre or Kevlar for the reinforcing, much stronger than glass but may be expensive or hard to find. Used just like glass.
However yes I am a fan of transom hung rudders. One boat that goes past here is in the 70ft class and has a suger scoop cut out for the transom hung rudder. This may help with cavitation. It also has wheel steering.
If you wanted to go transom hung rudder then you would benefit by having a top pintle extension so that the axis of pintles is vertical. Give your new rudder plenty of balance ie area forward of the pintle line. Make it as deep as possible. I would suggest you use polyurethane similar foam shaped then glassed over. Try to avoid making it too heavy.
lastly fit the bottom pintle as low as possible to minimise side loads which are as said huge. Strengthening of inside of transom would be necessary and even consider that the pintle may be torn out allowing water in to the hull. Some sort of sealing off of the area? good luck olewill

The rudder on my boat - Boomaroo 25 - is stern hung. There is a s/s frame on the pintles and the rudder hinges in this. It lifts up with a s/s rod attached to the rear of the rudder. I always swing it up out of the water and tie the rod to the pushpin, then tie the tiller hard over.
The rudder is a solid lump of wood sheathed in fiberglass and painted and is very heavy.
Ole will - why your comment about not making it too heavy? Should I make a replacement blade using the method you suggest?
Sailorbaz

 

[William_H]

Ole will - why your comment about not making it too heavy? Should I make a replacement blade using the method you suggest?
Sailorbaz

Hi Baz Yes I know the Boomaroo, nice boat. The reason I advocate a light rudder is more related to my own boat. The Castle 650 is very sensitive to fore and aft trim. On the swing mooring it sits with the last metre of the hull out of the water. With 4 people in the cockpit it just drags its transom in the water. Ideal is with the bottom of the transom just at water level. I get all neurotic and try to get a crew forward just to lift the transom a bit. The rudder as it is is quite heavy and I think I could perhaps half the weight with a foam rudder. So reduce stern weight. To be honest I don't think I will build a new rudder but it would be nice.
Meanwhile I avoid having an o/b attached. Although from my post on mast crutch you will see I have probably added a bit more weight in modifying the stern rail. Perhaps I am worrying too much about weight in the stern and probably doesn't matter for the Boomeroo. good luck olewill

 

[skodster]

Far easier to repair the skeg.

To repair the skeg properly would involve re-bonding the skeg to the hull from the inside.

Unfortunately, to gain access to the root of the skeg would involve cutting away part of the cockpit sole which then would be a repair job in itself. Once you had gained access to the area of hull where the skeg was bonded, the hull (over the skeg) would have to be cut away to allow a glassing up of the inside of the skeg to the inside of the hull. The hole in the hull over the top of the skeg would have to be re-sealed with grp to make it water tight.

Without cutting the cockpit sole, the job would be nigh on impossible to do properly.

Far simpler is to reinforce the back of the transom and bolt two pintles through. I would remove the vertical portion of the skeg, leaving the small vertical section for a possible electric inboard conversion later.