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Mast Pumping 1988 Catalina 36 MKI

May 20, 2019
22
Catalina 36 MKI GIG HARBOR
Hi All,

I searched the forum and didn't see anything on this topic. My 1988 Catalina 36 MKI, I've owned for 1 year, has a terrible mast pumping, shaking, issue in wind at anchor and dock. I went around and tighted every single stay except the forestay, got them super duper tight. They were way easy to tighten when I started, especially the backstay which now takes some force to tighten more. When I now tug on any of the stays it takes a lot of tugging force to get the mast to bounce/shake/pump, whereas before it took almost no hand pressure to get it to do it. So I think that is solved correctly...?

My real question is, no amount of tightening on either port or startboard, moved the mast side to side. From the inside, I can see the mast is resting port and aft in the deck hole. Is that normal? Using a plumb bob, but mast is not straight, but only slightly, and that's really because the entire boat leans to port, which is common on these as the galley and other weight is all over there. So i think the mast is most likely straight. See photos of the deck hole. Normal? There's also only 3 wedges. 2 toward the bow, and one on the starboard. Bow two are tight. Starboard loose as can be.
 

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Oct 22, 2014
14,543
CAL 35 Cruiser moored EVERETT WA
because the entire boat leans to port,
If trying to tension the boat stays you need two start with the boat level. Even if you need to add weight to starboard to take weigh off the port side. The boat needs to be sitting level on her lines.

Then you can start to fix the mast vertically in the mast's deck hole. Be sure the base is in the proper position on the keel step. Just because the mast goes thru the deck does not mean it can be resting any place it wants on the keel.

Once vertical you can start to tune the rig.

Note that tuning the stays is adding downward force to the mast pulling it into the keel step. As you tighten the stays you affect the whole boat. You do not want to make the rig tighter than it should be. This can deform the hull.

If this is not something you understand or feel lack experience, invest a few bucks with a good rigger.

There are a few here in the Puget Sound that can help make your sailing experience better.
 
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Jan 11, 2014
7,159
Sabre 362 113 Fair Haven, NY
It is probably time to detune the rig and start over. There are books that can help, the Selden mast tuning guide is a good reference (it is on their website). It may be worthwhile to hire a rigger, as @jssailem suggested, and have him tune the rig properly and teach you how to do it. It will cost you a few hundred dollars, but it will save your mast.

The location of the mast collar and the partners is not all that accurate. The mast should be centered over the midline of the boat. The hole the mast goes through may not be centered. This is not uncommon. Likewise the chainplates may not be equally placed.

Lots of things can cause mast pumping. Just increasing the tension on the shrouds and stays will not stop the pumping. There is a phenomena where vortices form around the mast in certain wind conditions. My mast pumps a lot in 4-5 knots of wind, but not in other conditions.

Hire a rigger or find a friend who is really knowledgeable to help you retune the rig. Be forewarned there are lots of guys in the marina who think they know more than they do. ;)
 
May 7, 2012
886
Hunter e33 Maple Bay, BC
If this is not something you understand or feel lack experience, invest a few bucks with a good rigger.
:plus:
Money well spent. Baseline your rig and watch and learn from the rigger so that you can do it yourself confidently in the future.
 
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Dec 28, 2015
1,105
Laser, Hunter H30 Cherubini Tacoma
I believe tightening by feel is in the same category as hand grenades......kinda close but not really. Get a Loos gauge to at least get them symmetrical as you straighten mast/tighten them.
 
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Apr 26, 2015
591
S2 26 Mid On Trailer
If you have a deck mounted whisker pole, move it to mast mounted. I did this on an Ericson 34 and it changed the flow around the mast just enough to eliminate the problem.
 
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Nov 21, 2012
250
Yamaha 33 Port Ludlow, WA
Brion Toss' shop in Port Townsend is now run by Ian Weedman, who apprenticed with Brion and has worked as a rigger for years. You would be hard pressed to find someone nicer or more knowledgeable. They held rigging clinics in the spring and fall until COVID. Give them a call and see when the next one is scheduled.
 
Jan 19, 2010
873
Catalina 34 Casco Bay
Your mast is not centered in the step. It is against the port side ( tight) with what looks like a finger width on the stbd. Start HERE! You'll need to free up everything.Stay away from wooden wedges. A boat with an innate heel is not always a good candidate for using a pendulum to center the mast. But, using a tape attached to the freed up topping lift you can measure to the top of the toe rail or center point of the chainplate to guarantee equilateral distance. Use the topping not the main halyard as it is either on the port or stbd sheave while the topping lift is centered to the mast head.
 
Sep 25, 2008
923
Macgregor & Island Packet VENTURE 25 & IP-38 NORTH EAST, MD
To help with your mast pumping at anchor, spiral wrap one of your halyards around the mast. This will help breakup the air flow.
 
May 20, 2019
22
Catalina 36 MKI GIG HARBOR
You are all Legends for replying with great detail! I already ordered rubber wedges. And I totally agree, this first time, I want to hire a rigger to both inspect and tune, but all those I've contacted are flakey. I can't get anyone to take my money!
 
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Jan 11, 2014
7,159
Sabre 362 113 Fair Haven, NY
You are all Legends for replying with great detail! I already ordered rubber wedges. And I totally agree, this first time, I want to hire a rigger to both inspect and tune, but all those I've contacted are flakey. I can't get anyone to take my money!
Call them and ask for a rig inspection for possible replacement and upgrading running rigging. While he's there ask him about tuning. Eventually you'll have to buy some rigging from him, but you probably need it.
 
Oct 22, 2014
14,543
CAL 35 Cruiser moored EVERETT WA
No idea who you have contacted and why you are getting that response.

The folks in Port Townsend at Toss's shop are terrific.

Bob Doyle is the Mast Whisper, working out of Everett WA.

The owner of the Consignment Shop in Poulsbo, I think his name is Kent, is one of the younger riggers in the area.
 
May 20, 2019
22
Catalina 36 MKI GIG HARBOR
Thank you. I actually just got off the phone with Cliff at Evergreen Rigging. Sounds like a great knowledgeable dude, and I'm officially on the books for two weeks from now. Thanks everyone again for all the replies!
 
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Oct 1, 2007
1,663
Boston Whaler Super Sport Pt. Judith
I believe the behavior seen here where the mast "pumps", or oscillates, is the result of the frequency of the wind or vortices off the mast exciting natural frequencies of vibration of the mast and rig structure. Generally, the frequencies of masts of this size would be below the shed vortex frequencies of the wind, so you would not expect the "pumping" behavior. But once the shrouds are tightened, the frequencies can change in an unpredictable way. The navarchs who designed the rig understand all this and the design of the spar and rig reflects their desire to avoid excitation of modes of vibration.

So, as was stated above, the best approach is to ease off on the shrouds and use a systematic approach to tuning the rig. Generally, the forestay and backstay are set to position the mast in the fore and aft direction, depending on whether any rake is desired. With no rake desired the mast is trimmed for vertical. The position of the masthead can be seen by using the main halyard to measure points on deck on each side and fore and aft. Next, port and starboard location is set by slowly tightening the uppers, again using the main halyard to determine port and starboard location. From there, the fore and aft lowers are trimmed to keep the mast straight. After a first run through to achieve verticality, for and aft location, and side to side location, everything can be slowly tightened down as desired, preferably after a light air sail to see first hand how the mast is behaving. Back in the day our Pearson 39 yawl had both masts stored for the winter layup and I was faced with this challenge each spring. After 2 or 3 years, it was second nature.
Good luck!
 
May 20, 2019
22
Catalina 36 MKI GIG HARBOR
Well I'm having a pro come out and inspect and tune. I just don't trust myself the first time alone. The mast is way off center in the partners. So it's definitely out of wack.

I did however test wrapping two spare halyards around the mast and it eliminated a lot of the pumping = disrupted that frequency.
 
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Jul 12, 2011
922
Catalina 36 1771 Ft Pierce, Florida
Great advice, and really glad you took it. If your rig is loose and the mast is moving around at anchor, it's not going to be pretty when you're out in a blow. Two more bits of advice: (1) Ask to go to the tuning yourself and learn - most pros don't mind, if you're respectful. You'll probably learn how close you came to having two shorter masts when the boat was only designed for one! (2) Consider replacing those wedges with Spartite, but get someone to help you set that up if you've never done it. For the C36, you only need the small kit, and it makes a world of difference in both tuning and water tightness (although it's not really a sealant).
 
May 20, 2019
22
Catalina 36 MKI GIG HARBOR
I totally wanted Spartite, but learned about it after I ordered the non-returnable rubber wedges from catalinadirect. But rigger said he's used those on Catalina's a lot and says they're actually a pretty good solution, though he also said Spartite next time. He also said no problem leaning over his shoulder so I can learn how to do this. Sounds like a good traveling rigger to me! Interestingly, the boat sails great in a blow as it is right now. We had it close hauled in 20 gusts to 25 last weekend and it was a beauty. Of course, that's the weekend I started questioning the tuning at anchor. Otherwise, I'd have not gone out. Slowly learning, but getting there!
 
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