If skeg damaged could you just removed it?

[infoanalysis]

I just bought a 25' Roberts full keel modified with skeg aft the prop. The boat is s steal with a brand new yanmar and trailer but the skeg is damaged. Says the wood core may have rotted inside the hull so can be moved with your foot while sitting on a trailer. The repair will require cutting into the cockpit aft the diesel ( not enough access from the aft berth) and also extensive work in fiberglass and demo. Instead of going through all of that I was wondering since so many modern designs don't even have a skeg would it be ok just to cut it off and glass over it-- enjoying my increased speed due to less drag or does this throw the entire dynamics off for the boats steerage, weather or leehelm etc. If that skeg is just to protect the rudder do I really need it considering it is on so few modern designs-- it's not like I am worried about UFO's as I cruise to Hawaii; this pocket cruiser may rarely even go into the ocean.

[Chotu]

Opening a little larger of a can of worms, a perfect solution would be to replace the whole thing with a balanced spade rudder of proper NACA foil shape and same area profile as the current rudder/skeg combo has.

But I’m guessing you’re thinking about doing this to save time as opposed to replacing the skeg.

Looking at the underwater profile, I’m afraid yes... you’ll introduce some lee helm if you remove the skeg. Its area in profile is non-trivial.

Ask Bruce Roberts if he’s still actively designing.

[infoanalysis]

thanks
yes to save time and that thing that keeps pouring into the hole in the hull -- money.
it looks like that skeg relieves some hydrostatic pressure on the rudder.
how can i get a hold of him?

[Chotu]

Originally Posted by infoanalysis

thanks
yes to save time and that thing that keeps pouring into the hole in the hull -- money.
it looks like that skeg relieves some hydrostatic pressure on the rudder.
how can i get a hold of him?

https://www.bruceroberts.com/

[noelex 77]

Originally Posted by infoanalysis

Instead of going through all of that I was wondering since so many modern designs don't even have a skeg would it be ok just to cut it off and glass over it-- enjoying my increased speed due to less drag or does this throw the entire dynamics off for the boats steerage, weather or leehelm etc.

No, unfortunately you cannot do this. Spade rudders use thicker rudder shafts and more robust internal bearings.

You could switch to a spade rudder (or perhaps a transom hung rudder, with tiller steering ) by redesigning the rudder and internal rudder mechanism, and achieve a good result from both a hydrodynamic and strength point of view, but it would be a lot of work.

The skeg portion is often not very strong. The boat designer Bob Perry once joked that for most skeg hung rudders it was the actually the rudder that was supporting the skeg. Consequently, falure is not unusual and you should be able to find plenty of information on how to proceed repairing the skeg.

Nigal Calder produced a long series of articles (I think in Professional Boatbuilder) on fixing the skeg on his Hylas. From memory it was initially repaired, but subsequently showed signs of failure and was completely removed and rebuilt from scratch. He provides plenty of detailed information about both the repair and complete rebuild options. Sorry, I don’t have a link, but a search should turn up the relevant article.

[Cadence]

Originally Posted by infoanalysis

I just bought a 25' Roberts full keel modified with skeg aft the prop. The boat is s steal with a brand new yanmar and trailer but the skeg is damaged. Says the wood core may have rotted inside the hull so can be moved with your foot while sitting on a trailer. The repair will require cutting into the cockpit aft the diesel ( not enough access from the aft berth) and also extensive work in fiberglass and demo. Instead of going through all of that I was wondering since so many modern designs don't even have a skeg would it be ok just to cut it off and glass over it-- enjoying my increased speed due to less drag or does this throw the entire dynamics off for the boats steerage, weather or leehelm etc. If that skeg is just to protect the rudder do I really need it considering it is on so few modern designs-- it's not like I am worried about UFO's as I cruise to Hawaii; this pocket cruiser may rarely even go into the ocean.

If I understand you? If she was designed with a skeg she requires it.

[Clivevon]

"Instead of going through all of that I was wondering since so many modern designs don't even have a skeg would it be ok just to cut it off and glass over it-- enjoying my increased speed due to less drag or does this throw the entire dynamics off for the boats steerage, weather or leehelm etc. If that skeg is just to protect the rudder do I really need it considering it is on so few modern designs--"

You've already had your answer - NO - but I am kind of sensing that you dont really understand what you are looking at? Please forgive me if I am wrong.

The rudder shaft is sure to be secured to the skeg - certainly at the bottom. So if you cut off the skeg, you lose your rudder also. Many people prefer a skeg hung rudder as being more robust, but as someone has said it depends on the design.

Modern designs mostly have a spade rudder - meaning the rudder shaft is only supported by a bearing at the top, where it leaves the hull. They are designed to be that way from the start & the bearings & shaft are sized accordingly.

I would be pretty sure that repairing or rebuilding that skeg would be much easier than trying to convert a skeg hung rudder into a spade rudder - & you will end up with a much better result if you do it right.

Not a small job. Good luck.

[Cheechako]

Any wood in there shouldn't be structural...? This is a fiberglass boat right? I'm surprised the skeg is that flimsy. Can you add structure or glass to the skeg inside?
Really we need a pic of the inside back there to see what's going on....

A spade rudder can be done, but you may need a stronger rudder and will need more structure inside, tube glassed in, bearing setup etc to support it.

The easiest if you dont want the skeg may be to put a rudder hung off the transom if the transom is near vertical. with pintle & gudgeons..

[Clivevon]

A tiller steered transom hung rudder might be a possibility but it would need to be big to regain the lost skeg area & so you would have to balance it with some area forward of the pivot point to make up for its size so you would be into a whole new ball game of effectively redesigning the boat. I would fix the skeg.

[Cheechako]

Is this the boat model? (some decks/cabins are different)

[Cheechako]

Skeg reinforcement:

[Cadence]

Originally Posted by Cheechako

Skeg reinforcement:

That looks more like deadwood to me.
He might consider having a metal skid plate fabricated with sides to reinforce the skeg. It is only a guess not seeing his situation

[Apollo366]

If it were me I'd contact Bruce Roberts and do what he says, He's probably seen the problem before and knows the best solution.
And yes, it probably involves removing all the old skeg & making a new one & reinforcing it better than the original.

Wayne

[infoanalysis]

Yes that is the identical hull topsides are indeed different

[infoanalysis]

Oh I did not know marine architects are so fussy with the balancing of the design rudder/skeg with the keel. I thought it was just "if it looks good build it." There must have been a lot of trial and error hulls before they figured out designs that work unless they have cad cam as today or very deep into the maths and geometry. My father used to talk a lot about The Webb Institute near where I grew up. They did all that stuff he said and it was a very elite group of people who were admitted.