Rudder thunks

[Cpy23ecl]

Finally got my new eclipse out for the first time and am hearing a groan followed by a thunking sound with each wave.  Also feel a vibration in the tiller with each thunk.  My first thought is the rudder blade hinge bolt wasn't tight but it's as tight as I can get it.  I hear the groan followed by the thunk even with the tiller tied off to the boom arch and pulling on the tiller to make sure the tiller isn't moving at all.

My other thought was that its the swing keel but nothing changes between the keel fully up or fully down.

Anyone else have this?

Any other ideas as to what it could be?

Fred

[Jim in TC]

You probably would have detected this as part of your inspections/trials: when I was getting extra play in the tiller and some noises I found that a pintle had come loose, though still held in place by virtue of a design putting the top end into the framework that holds it and a sleeve that prevented it just dropping out. This on a SunCat with Ruddercraft after market rudder.

[alsantini]

Fred.  First off congrats on the Eclipse.  I suspect that the pintle bolts are not tight.  Look at the rudder connection points.  Does either of them move during the thunk?  If so, pull the inspection plate and use a wrench on the nuts that run through the aft end of the rudder post.  It might take someone else steering while you hang off the stern, to see movement.   You really only have three choices.  Top and bottom connection bolts or the rudder is moving within the rudder cheek plates.  If the rudder cheek plates were welded with too much clearance it might thunk.  It would be time to call the factory at that point.
Enjoy the Eclipse....  Sail On,  Al

[Cpy23ecl]

I could detect no play whatsoever in the pintles, rudder cheek plates, rudder blade, or tiller mounting hardware.  As far as I could tell it was coming from under the waterline but I can't be sure.  The way it was timed to the wave passing by the rudder I thought it was the blade moving in the rudder cheek plates, but I could detect no motion there.

It looks like its going to take me some time to adjust to this boat.  My first sail left me feeling that it doesn't perform anywhere near as well as any of my previous boats including my 23.  Started the sail with a moderate breeze, I'm guessing in the 6 to 8 kt range, and I would have sworn I was dragging a sea anchor from the stern the way it felt.  As the wind picked up to the 10 to 12kt range, it sailed significantly better but I had to trim the sails to what in any of my other boats would have been close hauled even though the wind was coming off the beam.  As soon as I eased the sheet tension to what I normally would trim for a beam reach the telltales would start drooping and the both the jib and main would start to luff and lose shape.

Hopefully I'll figure it out soon, but didn't expect that it would feel so different.  I've been sailing for 35yrs and the only time I had this much trouble trimming sails was the one day where I actually had the wind coming from a different direction at the mast head than it was at the boom.  Never saw anything like that again.

Thanks for the input.

Fred

[Renae]

The rare clunks on my Suncat come from the centerboard, usually under conditions of lateral stress (e.g. catching a large wake abeam).  Personally, I think they mean nothing other than lift and drop.  Check the condition of your CB pennant on a lift every few years, or, like me, get out the ol' mask and snorkel on a sunny day.

[Cpy23ecl]

Mine clunks with every wave and still clunked with the centerboard up.  Wave height was in the 1 to 2 ft range so was pretty calm for Lk MI.

[kahpho]

Yer welcome.

[slode]

On my Eclipse the pintle bushings were loose fitting when I got it.  The rudder would clunk back and forth over any change in force direction, like when rolling over a wave on a beam reach.  Tightening the bolts did not help much as it was the actual fit of the bolts through the bushings.  I replaced the bushings and changed to 8mm vs. 5/16" hardware and that greatly improved things.  I would suggest checking the fit on those.

The Eclipse is no speed demon, but she isn't a slouch either.  I've sailed circles around a West Weight Potter 19.  Not that that's a fast boat, but it was significantly slower.  I'm sure you'll get her figured out.  The vang and traveler are worthwhile controls to utilize in anything other than a close reach to keep the proper twist and to keep mainsail off of the shrouds.   

[Cpy23ecl]

Went out sailing for the second time yesterday and checked the rudder pintles carefully before leaving the slip and can't detect any play in them at all.  Oddly enough I only felt a couple of faint thumps while sailing although that may be because the lake was calmer than the first time.  So still no idea why the thunking occurred but I expect I'll figure it out eventually.  Thanks for all the replies.

Fred

[Andre]

I've no Eclipse experience, just PC and HC but ...

Could it be the gudgeon casting isn't firmly attached  to the hull? Also maybe the thunks aren't actually coming from the rudder but you're just feeling them through the tiller. In that case I would check centerboard play, outboard motor and bracket, battery and gas tank looseness (I don't know where these are placed), even the mast (step?) and standing rigging among other things. Is it more obvious on one tack or the other or one point of sail?

Also on my HC I put a homemade polyethylene "washer" shim on the pinch bolt holding the rudder itself onto the pivoting casting. This wasn't prompted by any thunks but I wanted to minimize the casting flex required to pinch the rudder after seeing what appeared to be a fatigue failure crack in the casting on an Australian HC.

Just some wild guesses ....

Andre

[Eagleye]

Hi Fred,
Congrats on your Eclipse!  What year is she?
One thought on your question. When sailing, is the rudder in the fully locked down position.  The stainless control rod wants to be hooked properly to keep the rudder locked down.  Check out this thread which might help understand this situation.

https://cpyoa.com/forum/index.php?topic=6539.msg46970#msg46970

Good Luck,
-Allen

[Cpy23ecl]

Eclipse is a 2021 that was delivered just before Thanksgiving last year.

I've checked the gudgeons they are securely attached.  I'll need to check the gas tank as I know that can slide around in the starboard cockpit locker but didn't think to check that while I was out on the lake last time.

The rudder was definitely fully locked down.

Hopefully in the upcoming sails I'll get it located.

Thanks for all the responses.

Fred