Mast Pumping

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prestonrockstar
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Mast Pumping

Hi all,

I've owned my Catalina 36 MKI for a year now. Previous owner had just had the rig inspected. in 10+ knots of wind at anchor or at dock I get mast pumping and I can't imagine that's normal. Is it though?

I wrapped two spare halyards around the lower mast below the spreaders which aleviated pretty much all of the issue. But is there something more permanent? Is the rig just not tuned correctly?

Thanks,

Preston

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Sojourn
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Posts: 171

Preston,
The mast is out of tune.  On relatively calm day at the dock, loosen the rig.  Then tighten the lower shrouds to keep the mast vertical fore and aft and side to side.  Then tighten the head and back stay to center the mast and keep it vertical.  Then tighten the upper shrouds to keep it vertical side to side and fore and aft.  The should be no deflection to any thing by simply applying finger tension to stays or shrouds,  

Then go out for a sail in modest weather.  On  a beat, sight up the mast and correct any deflection on the stays or shrouds to keep the mast vertical.

Lou Bruska
Sojourn
1985 C-36 MK-1 hull 495

Lou Bruska
Sojourn
1985 C-36 Mk-I TR #495
Eldean Shipyard
Lake Macatawa (Holland, MI) Lake Michigan
Rallyback@comcast.net

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Sojourn
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Posts: 171

As a follow up, check mast wedges for loseness and/or missing wedges which could cause the mast move in the mast collar.  Also check to mast step and the base of the mast.  Damaged or malformation there could be the problem.  Lastly, look for evidence of the mast step moving.  Some of the boats in the past reported rotting under the mast step.  Look for cracks around the step and softness or sponginess there.    I have two friends that have had that problem.  One on a C-36 and the other on C&C-39.  If all is well, tuning may be the solution.

Lou Bruska
Sojourn
1985 C-36 MK1, hull 495

Lou Bruska
Sojourn
1985 C-36 Mk-I TR #495
Eldean Shipyard
Lake Macatawa (Holland, MI) Lake Michigan
Rallyback@comcast.net

prestonrockstar
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Posts: 16

Thank you for the replies! There are 3 wedges I can see from below. Two are tight, one is loose as all can be. Mast isn't centered in the hole, it's aligned to the left. I'm guessing that's no good. I assume it aligns properly when tuned properly. How scary is it to tune on your own for the first time? No special tools required just loosen and tighten and visually inspection the mast?

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Sojourn
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Preston,
Three wedges is not enough, they should surround the mast, at least six.  As for tuning, at dock is the start.  On the water is the fine tuning with mast under load.  Both are important, start with mast vertical, keep it that way under load.  It takes a little practice, but your eyes won't deceive you.

Good luck!

Lou
 

Lou Bruska
Sojourn
1985 C-36 Mk-I TR #495
Eldean Shipyard
Lake Macatawa (Holland, MI) Lake Michigan
Rallyback@comcast.net

prestonrockstar
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Posts: 16

So...I think I fixed the mast pumping. At the dock I can make the mast pump with ease if I yank on any of the stays. So I literally just tighted them all up...A LOT. until it's quite difficult for me to make the mast pump by hand. I wonder how "hand tight" the stays should be as I'm cranking. The backstay is pretty hard to turn now, whereas it was super easy when I started.

Also, nothing I did moved the mast side to side or forward to back. Inside, you can see it still sits port and aft in the deck hole. See photo's. Is that just normal?

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Chachere's picture
Chachere
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Posts: 825

From the pictures it looks as if you are missing some of the wedges that keep the mast centered in the opening.

Matthew Chachère
s/v ¡Que Chévere!
(Formerly 1985 C36 MKI #466 tall rig fin keel M25)
2006 Catalina Morgan 440 #30.
Homeported in eastern Long Island, NY

prestonrockstar
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Posts: 16

Ok...so it is definitely supposed to be centered then. Has anyone had to tackle recentering? I ordered the rubber wedges from Catalinadirect already, now reseaching and planning ahead. But no articles really go into any detail that I can find. I supposed you have to remove the mast boot, and then I guess just loosen every stay there is to allow the mast to be pushed or pulled into center so you can then hammer those wedges into place all the way around? I'm a little worried about loosening stays because I've never done that before, atleast not enough to allow the mast to move. Or will it still be too heavy to move? Do you just have to start wedging and by hammering in the wedges it centers the mast? Maybe you don't loosen the stays at all?

I truly appreciate all the replies. I'm tring to do the research myself,  just not finding much on this topic.

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Chachere
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Prestron -- you wrote "I guess just loosen every stay there is to allow the mast to be pushed or pulled into center so you can then hammer those wedges into place all the way around?"
You may find that you don't have to loosen the stays to do this.   I have had a wedge or two come out, and the mast was loose in the opening, and I was able to nudge the mast over and hammer the wedge back in. 
Either way, you'll probably want to check the mast afterward for alignment/trueness, and if necessary adjust the stays.

 

Matthew Chachère
s/v ¡Que Chévere!
(Formerly 1985 C36 MKI #466 tall rig fin keel M25)
2006 Catalina Morgan 440 #30.
Homeported in eastern Long Island, NY

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Sojourn
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Basically, you got it.  As long as the threads are fully engaged in the turnbuckels all's well.  Loosen the back stay and all the rest of the shrouds.  The head stay may be covered up by the furler, it's no a big deal.  Yes, the mast boot needs to be loosen and raised.  One tip is: before tightening anything use a level below deck on the mast in two planes fore/aft and side to side.  This is the basic check to see if the mast is in vertical between the mast shoe and mast collar after the shims are in.  If the mast is vertical below deck, but off to one side, the shoe and collar might not actually be aligned.  Once everything trues up below deck, you can tune the mast at the dock, per above.  

Lou Bruska
Sojourn
1985 C-36 MK1, hull # 495

Lou Bruska
Sojourn
1985 C-36 Mk-I TR #495
Eldean Shipyard
Lake Macatawa (Holland, MI) Lake Michigan
Rallyback@comcast.net

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Clifford Bassett
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Posts: 30

That advice from my friend Lou is what you need to do.  After you pull the boot up out of the way.

1.  Loosen all shrouds and the backstay.
2.  Put your wedges in, starting on the side that is in contact with the collar. 
     Make sure that the wedges only contact the collar, NOT the hole in the deck.
3.  With all the wedges in.  As many as you can get in the opening. 
     Make sure they do not contact the hole in the deck, they should only contact the collar. 
     You should adjust the upper shrouds to hand tight.
     Then take the Main Halyard and adjust it to just comes into contact with the outter genoa track on the port side.
     Then, using the same tension on the Main Halyard it should touch the outter track at the same point on the starboard side.
     This will center the mast head.
4.  Now you can adjust the lower shrouds uniformily, keeping the mast in column. 
     You can check whether straight by siting up the Main Sail Track,
5.  It has been my experience that the shrouds on a Catalina need to be quite tight.
6.  You can now tighten the Backstay. Very tight.
7.  You can check your tension as Lou suggested by going out for a sail and site up the Mast Main Sail Track.
8.  The Mast should stay in column under load.

NOTE :  The photo showing the wedge in the opening, that wedge is inserted incorrectly.  It appears to contact the opening in the deck.  That is a NO NO !  It should only contact the collar.

I hope this helps,  

Captain Cliff

Clifford Bassett
s/v " Red Dog "
1984 C-36 Hull # 260
M25 SR/FK
​Holland, Michigan
 

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Gsmith
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Posts: 117

Not to hijack this post but I would be interested in hearing from other 36 owners on what materials their mast wedges were made of and how many used. Mine appear to be home made from some kind of hardwood. They work fine but makes me wonder what the factory setup was..

Thanks

92 MK 1.5
1231
 

Gary Smith
93 MK I, Hull #1231
Std rig; wing keel
M35A Oberdorfer conversion
 

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Chachere
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Our boat has 4 hardwood wedges, no idea if they are factory (36 years on, I doubt it!).

Matthew Chachère
s/v ¡Que Chévere!
(Formerly 1985 C36 MKI #466 tall rig fin keel M25)
2006 Catalina Morgan 440 #30.
Homeported in eastern Long Island, NY

prestonrockstar
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Posts: 16

I purchased the rubber ones from Catalinadirect. Haven't put them in as I'm pretty nervous about loosening all the shrouds and backstay. I attempted it the other day, got them really loose, and the mast doesn't move at all...

I hammered one in to get the mast off resting on the port side of the hull. But that's as far as I went as it seemed odd to me with all that slack that the mast wasn't moving side to side or forward at all on it's own. I can't even hammer a wedge on the aft side of the mast because it's resting tight against the partners. There's a rubber strip there that someone put in place on purpose, so I am starting to wonder if the hull hole simply wasn't a straight cut, and the mast was actually straight up even though it was touching the hull. Unfortunately, the rigger I had coming out is ghosting me, like the others. So have to start making new phone calls yet again.

prestonrockstar
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Well, after trying to  hammer the rubber wedges in, which all but two are FAR TOO fat for our boat, my oppinion is the  wooden factory wedges are superior. They "wedge" in like wood does. The rubber goes so far, then the hammer just bounces off. They don't go down far enough and the rubber is thick enough that there's no great way to shave them down to size. They can't be hammered in far enough to allow the mast boot to fit. So I'll need to find a way to cut the tops off. They're in their solid, just too tall. I may just make some out of wood instead.

The next issue I find is with the manual itself. It says the shrouds should be tight but basically not tight when at dock. That's ridiculous. When they're tight but not tight the mast bounces all over the place when any amount of breeze runs across the shrouds. The manual makes absolutely no mention of tension on the back stay. Pretty sub par if you ask me. So I'm going around tensioning based on the other boats on the dock, which are quite tight, very, very tight all around. I now it it tight enough that when I wiggle the shrouds and back stay the mast doesn't wobble and bounce and pump. But it's WAAAAAY tighter than the manual says they should be. I hear the boat "adjusting" to the tension. I hope it's because the rig was floppy loose and it's just the retightening it's going through.

I was able to move the mast foreward just enough to get it off the hull, but it WILL NOT move any more forward. Seems odd. But whatever, it's not on the hull anymore.Side to side it's centered in the colar at least. Just not fore and aft.

Hoping I have done well. I don't like hearing the boat "crack" if you will. Pretty sure it's just resettling into being tight.

 

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Chachere
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There was a thread a while back on mast tuning: www.catalina36.org/forum/technical-discussion/mast-tuning
I believe the C36IA has (or had) a Loos gauge in its members toolbox, but they are not very expensive: defender.com/product.jsp?id=180145#
 

Matthew Chachère
s/v ¡Que Chévere!
(Formerly 1985 C36 MKI #466 tall rig fin keel M25)
2006 Catalina Morgan 440 #30.
Homeported in eastern Long Island, NY

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Clifford Bassett
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Posts: 30

Well,  It sounds like your on your way to total success.  Before you go too far with tensioning, make sure the turnbuckle inside the Boat is snug. It has a purpose.  I had my rig tuned by a professional for many years and I can assure you, he made my rig very tight.  The backstay tension is a different subject.  The Backstay tension controls how much " sag " you feel you want in your Headstay.  If you ever want to go closehauled ( into the wind ), You need a considerable amount of tension.

Good Luck,

Clifford Bassett
s/v " Red Dog "
1984 C-36 Hull # 260
M25 SR/FK
​Holland, Michigan
 

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mike37909
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Posts: 161

I dont think they cut the hole in the deck in the exact correct spot. My mast isnt centered on the deck cutout either. I tried to center it with the shrouds it made no difference.  My mast used to pump bad and i did have rotten mast step. I replaced it.  Not sure if still pumps but I haven't noticed it.  

Catalina 36 MK1
1984 Hull #306

 

prestonrockstar
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Posts: 16

Thanks Mike, it is helpful to hear that others don't/didn't/can't get a totally straight mast. Mine is far better now, and I ended up ditching the rubber wedges and made my own out of oak.

Regarding checking for a rotting step, I looked around and none of the floor accesses or the little door near the mast give access to see the mast bits that run all the way to the keel. Am I missing something obvious? The area where the mast goes through the floor looks and feels fine. The "collar" around the mast on the floor is solid. Where else would one look to see and inspect more?

Thanks again everyone for so many replies. This has been a frustrating project for me simply because messing with rigging seems like it would be a whole lot more serious to deal with than I think it is in reality. Even the manual essentially says use your common sense and then go out and test it and adjust. So I think a lot of this is me way over thinking it.

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mike37909
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Posts: 161

If the mast step is rotten bad you will get cracks in the fiberglass around the mast step casting.  When I pulled my mast it pulled the fiberglass out in the exact shape of the mast casting.  The casting came out also with the mast.  My shrouds went loose in heavy wind but I already knew it was sinking.  I fixed it with ironwood and glass

Catalina 36 MK1
1984 Hull #306

 

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KevinLenard
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Posts: 215

Per the reply above, there is nothing that connects the aluminum mast step base plate to the floor or keel other than maybe some SS screws.  The mast sits on the plate, the plate sits on solid fiberglass down to the hull over the keel.  In the older boats ('83 - '86?) the 'Catalina Smile' occurred because they had places a thick piece of plywood that the forward-most keel bolt went up through (as it rotted the keel dropped), but I don't think there was plywood under the mast step.  However, it might be that, as our colleague above noted, dampness, the pressure of the rigged mast, the slight 'wiggling' of the base of the mast contribute to the base weakening and compressing.  Tapping around it might tell you if there's a different sound as you move to starboard away from the base.  Pulling the mast isn't a terribly difficult last-ditch effort to see if there's a problem, but a call to the Catalina engineers could also help ID the possible risk from their historical experience with your model and vintage.

Kevin Lenard
"Firefly"
'91 C-36 Mk. "1.5" Tall Rig, Fin Keel, Hull #1120, Universal M-35 original (not "A" or "B")
CBYC, Scarborough, Lake Ontario, Canada

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mike37909
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Posts: 161

Yes they are 4 lag bolts self tapped into the cedar mast step block.  Mine came out like mulch.  filled two 5 gallon buckets.

Catalina 36 MK1
1984 Hull #306

 

jwskawski
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Posts: 13

I'm following this with greeat interest...

Feeling that mast pumping at dock ans also on a recent sail suggests our rig is out of tune as well.  There is to my eye sag in the forestay under load.  All else looks decently in column, centered side to side at rest.  Removng mast boot and (clay!) from underside reveals Spartite collar with leading edge slightly raised.  To me this means that the mast is no longer quite where it needs to be in the collar.  Back stay fels just as tight as can be and port side turnbuckle (split back stay) was tightened such that there is very little distance to left to go.

Any thoughts on if it might make sense to ease back stay and take up the forestay, ease off on shrouds and while loose, re-set the spartite ring wedge, then tighten all down as Lou and another gentleman outlined?

1992 Mk 1.5 #1176
Tranqulity
 

J Wm Skawski
Tranquility
1992 Wing
#1176

prestonrockstar
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Posts: 16

Had a rigger out yesterday. Inspected the rig and tuned. He does not think tuning was the cause nor will aleviate the mast pumping issue. He was not able to move the mast anymore forward than I, whish is still quite aft in the colar. We literally ran out of backstay trying. So, it came that way from the factory. Now, I have not gone out to test for mast pumping yet. Maybe a fine tune somehow fixed it, but we both doubt it. Sounds like wrapping extra halyards around the mast in wind at anchor is the solution to disrupt the air flow.

two-rocks
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Posts: 74

I have mast pumping at the perfect angle and wind - not sailing, just at a mooring or dock. light wind, 30-40 degrees port or starboard.

my solution, more cocktails. 

I have tuned, de-tuned, re tuned, straight mast, mast bend, wrapped halyards for vertex shedding, and on and on.  My mast collar has 20+ custom cut wedges, full coverage. As others have said, the mast will not necessarily be centered in the deck penetration, and centering there is not the goal. 

I might Richard with it more this year, or not  

 

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pkeyser
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Posts: 668

When you experience the pumping, try grabbing the lower shrouds and pull them in to apply more tension and see if that dampens the vibration.

Think of the mast as a tall skinny spring supported primarily by the stays at the top. Every spring system has a resonate frequency - in this case energized by passing air flow. The resonate frequency can be changed by the stay tension (reducing or increasing the downward spring compression), and it can also be dampened by changing the level of support over the course of the spring's length (via the lower shroud tension). My guess would be that the stays are applying too much compression to the mast.
An easy check to see if they are too loose is to pull on them with your crew and observe the impact on pumping. If it continues or worsens, then go the other direction and reduce the stay tension. 

Paul & Wendy Keyser
"First Light"
Rye NH
2005 C36 MKII #2257
Wing, M35B

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