sailboat mast deck collar

Mast Chocks – Traditional vs Technical

Like many construction features on a sailboat, there is more than one way to support a keel stepped mast at the deck collar and seal this opening from rain or seawater. In the past 6 months we have chocked our mast 2 different times with two different techniques. First we used the more traditional approach using hardwood wedges for chocking and a mast boot to seal out water. Most recently we used the Spartite polymer “cast in place” mast chock and sealing ring.

Our boat is a 1981 Whitby 42 center cockpit ketch. The main mast is keel stepped passing through a robust fiberglass deck collar on the cabin top. We sailed over 10,000 miles with the hardwood wedges that were in place when we purchased the boat. They were likely quite old as many of them were splintered on the ends from being hammered into place over many years of mast installation and removal. Since the boat was based in Maine, this was done each winter for storage on the hard.

Last Spring, near the end of a particularly lively 3 day passage from Belize to Florida, I noticed a creaking noise coming from the area of the mast collar. Unfortunately, our mast passes through the deck into a box shielding the mast from the interior. A quick inspection of the mast chocks is not possible because the top of the chocks are covered by a mast boot that is not easily removed and the bottom side is inside the mast box. There is a floor to ceiling panel of the mast box that can be opened by removing about a dozen screws. To better troubleshoot the creaking sound at the mast, I opened this panel and discovered that one of the hardwood wedge mast chocks had fallen through the opening allowing all the other chocks to loosen and the mast was beginning to move within the mast collar. As you can imagine, this condition could be particularly dicey on a long offshore passage. As a quick remedy, I reinstalled the mast chock that had fallen out of place and tightened all the chocks with a rubber mallet. I re-used the mast boot that was in place but noted that the water tightness was likely compromised.

Before departing Maine in the Fall of 2017 for our trip to the Eastern Caribbean, I rebuilt the mast chock to assure that it would be robust for our planned offshore passage. I was able to purchase a half dozen new hardwood wedges from the Landing Wooden Boat School in Rockland, Maine. I also needed to replace the sealing material used for the mast boot. When we purchased the boat, the mast boot was a two piece construction. The inner layer was a soft, sticky black membrane material similar to ice and water shield used in home construction. This material was reusable to a degree but after years of manipulation, had developed a few holes. This layer was wrapped around the mast and secured top and bottom with giant hose clamps. The outer layer was a vinyl covering that wrapped around the mast and deck collar and was closed with Velcro. I could not find the exact membrane material but I realized from my construction experience that Vicor window and door flashing was very similar and likely a fraction of the cost.

Traditional wood wedges supporting the mast

Grace Vicor window flashing makes a great sealing barrier for a mast boot. A white vinyl boot covers this for aesthetics.

With the new materials in hand, I disassembled the mast chock in Rockland Harbor and reassembled with the new wedges and sealing material. Overall, I was pleased with the outcome but not fully convinced all our problems would be solved. The new sealing material looked great so I was not concerned with leaks. The bigger issue with the wedges I used is that they could still fall down into the deck collar if they loosened up over time. A better arrangement with wooden mast chocks is to cut them in a way that the top of the wedge has a lip that will stop the wedge from falling too far down into the collar. This requires custom cutting each wedge after measuring the gap between the mast and collar. The wedge must be cut so that it wedges in firmly without bottoming out on the lip at the head of the chock. I did not have the time or the resources to custom cut wedges so I buttoned up the project with the less than optimal wedges and headed south.

At the Annapolis boat show, I revisited the project by chatting with the many riggers with booths at the boat show. After several good discussions I decided that a Spartite mast chock was a great alternative to traditional wooden chocking. The Spartite Mast Wedge Replacement System comes in two sizes, small and large. For our mast, I purchased the large kit. I did not get a chance to install the Spartite mast chock before heading south, so the kit stayed in storage until we found a good spot to complete the project. One of the things recommended for installation is that you have a calm anchorage so that the mast is not swinging with wakes and surge. We found just the spot in the lagoon in St Martin.

The first step in the process is to remove all of the existing chocks. I was worried that my mast might move within the deck collar when I did this. I was pleasantly surprised that my mast moved less than 2mm when I removed all of the chocks. I left all the rigging tight in spite of the recommendation in the instructions to loosen rigging.

The Spartite kit includes all items required to complete the project except for standard masking tape. The Spartite mast chock is cast in place using a 2 part polymer compound. To create the form to pour the liquid into, you need to first create a dam within the deck collar to form the bottom of the chock. At the top you also create a circular form of masking tape to create the top lip of the chock. The Spartite kit includes foam insulation and modeling clay to pack between the mast and the deck collar to form the bottom dam. Standard 2” masking tape is used for the top form. Once the forms are complete a very important step is to apply the Vasaline supplied to the inside of the deck collar. The Vasaline is used as a mold release so that the polyurethane chock does not bond to the inside of the deck collar. It is absolutely necessary to have this mold release so that when the mast is removed at a later date, the polymer chock comes out of the deck collar. As an option, it is also recommended to coat the mast so that the polymer chock may be slide up the mast after the mast is removed. Once the forms are in place and the Vasaline applied, the last step is easy. The kit includes 2 mixing buckets and pre-measured cans of the 2 part polyurethane compound. You simply mix the two parts together and then pour the liquid into the form around the mast. The material hardens quickly and within a few hours it is firm although the center remains curing for a couple of days. The instructions recommend not sailing for a couple of days to assure the material is fully hardened.

Based on our experience, we would strongly recommend the Spartite solution. It is simple to complete and the result is a mast chock that will not loosen in rough conditions. It is also completely watertight. No mast boot is required for sealing purposes. We fabricated a canvas mast boot for cosmetic purposes.

Masking tape creates the top of the form with modeling clay sealing the bottom

Modeling clay between deck collar and mast creates a seal so that polymer can be poured in from above

Cured polymer creates a one piece solid mast support replacing wedges

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Optimist Maststep

Mast Step Slide, Cup Style

Optiparts mast collar - grey.

The Optimist deck collar is made of Delrin to create minimal friction between the sleeve and the collar. The oval inner diameter allows the maximum fore/aft and minimum side play and the tapered inner diameter allows the mast to be raked. 4 countersunk mounting holes. Hole size in deck: 57 mm.

The 1210 has a seperate sleeve which is fitted around the mast at deck level and protects the mast from wearing.

**Note, if you have a black gold mast with a grey sleeve on it, you will need this mast collar!

S/V Perspective

Following the adventures of Sailing Vessel Perspective

Installing the mast deck collar

For those of you who are non-sailors, our mast penetrates the deck and is ‘stepped’ on the keel.  Where the mast penetrates the deck, there is a metal collar to reinforce the area and stabilize the deck. 

Our old mast collar was completely corroded.  The aluminum actually discintigrated when I was trying to remove it.  

The next morning, sanded and cleaned the area with acetone.  We marked the new hole pattern and began drilling.  The first hole was stressful.  It’s amazing how fast a sharp drillbit will go through 3/4″ fiberglass.  

I applied a good base of 3M 4000UV as bedding material and bolted it all together.  All in all, easier than I though to install. 

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Grey Optimax Deck Collar goes with the Mast sleeve. This replacement collar does not include the mast sleeve but is designed to fit around masts with the sleeve installed.

• Fits masts with installed mast sleeve (not included)

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Deck compression under in and around the mast collar

• Thread starter Surfah
• Start date Dec 16, 2019
• Catalina Owner Forums
• Mid-Size Boats

I recently bought a 1987 30 ft Catalina. I paid for a survey to be conducted however due to a lack of professional due diligence he didn't catch the fact that the area in and around the mast is sunken and compressed into the deck. Has anyone out there had a similar issue with the mast and how did you fix it? I'm guessing that I'll have to remove the mast tear into the deck and remove whatever material is found underneath. After removal I'll have to re-fiberglass and/or epoxy the area until it's level once again.  

Soft deck repair under mast step

If the surveyor is a professional you may have recourse with him or his insurance company. Surveyors are supposed to find stuff like that. Their reports are often written with large loopholes but a deck problem around a mast is hard to explain away. How did you find the problem?  

I had a rigger come to the boat to tune the standing rigging as per the recommendation from the survey conducted barely a month ago when I was in the process of purchasing the boat. The rigger immediately noticed the issue upon walking up to the boat.  

Surveyor: " A month later huh? Well is was fine when I inspected it. I bet you tuned it and applied too much down force."  

Don S/V ILLusion

The compression post won’t compress/contract so it’s likely a problem where the post rests on the keel. Lots of Catalinas were built with a wood base which is the dumbest thing I’ve ever seen. The wood gets wet, rots and you have a sunken deck at the step. This isn’t a trivial problem and should be corrected depending on the value of the boat. I would definitely find out if the surveyor has E&O insurance. Most do. Not seeing that was definitely negligent by the surveyor. The lesson here never blindly depend on a surveyor. Do your own due diligence carefully inspecting any boat purchase before it’s too late. Too many incompetent surveyors in the world.  

We had a Cat30. The surveyor was about to miss this issue also. I had done some reading and suggested a more in-depth look. We were able to punch a screwdriver through the forward wall of the bilge. In the end, we bought the boat with an agreed upon reduction to account for the mast support issue. There used to be a number of fixes posted on the yahoo Catalina 30 group site- don't know if that group is still available. All methods involved completely removing the old mast step. Some fixes were based on screw jacks placed on a new base and supporting the compression post. Some used epoxy coated wood (which I would never do) . I used Trex decking material with fibrous Bondo in between layers to keep things stable. The Trex has low moisture absorption and more than adequate compression values (900 psi). The last two layers were opposing wedges to allow me to adjust to the correct height. You still might also have a deck issue- wet balsa core at the deck step. Good luck.  

Mast Step on tall rig Catalina 30

SBO Weather and Forecasting Forum Jim & John

Srufa. This is a critical issue. Even a DIY repair will take money and considerable time. This devalues the boat. Certainly the broker or the owner would have known about the issue.  

JRT said: Sorry to hear that, there are a lot of mast step repair threads on here that I have read. I'd plan to remove the mast then the compression post from inside, the cut the inside below the mast step out instead of the deck to repair it. try looking under Cataline 30 mast step repair here is one Soft deck repair under mast step The fiberglass is cracking around my mast step, looking exactly like the photos posted in this closed thread: http://forums.catalina.sailboatowners.com/showthread.php?p=1026954 After removing the mast step plate, I could dig out wet wood from the hole where the wires go through (after... forums.sailboatowners.com Click to expand

Had same issue on 1977 c27. The root of the problem is rot at the base of the compression post, which needs to be removed and replaced. You can't fix the problem on deck until the the punky wood is removed and replaced below. As mentioned above, a screw jack can help reinforce the mast and be incrementally adjusted, but to fix it right, you must repair the base first.  

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Opti Deck Collar w/ Mast Sleeve

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Description

Racing deck collar with an oval and tapered inner diameter. The oval inner diameter allows the maximum fore/aft play and minimum side play. The tapered inner diameter allows the mast to be raked. 4 countersunk mounting holes. Hole size in deck : Ø 57 mm

Comes with a separate sleeve which is fitted around the mast at deck level and protects the mast from wearing.

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Vinyl Mast Boot - Protect Your Boat from Drips Down The Mast

• CHECK YOUR FIT - This model fits masts with circumferences of 23” and larger with corresponding mast collars of up to 37” (584 to 940 mm)
• CONVENIENT DESIGN - Made of extremely flexible UV resistant vinyl. Designed to fit a number of sizes of mast with deck collars of the same basic shape.
• CLEAN LOOK - Molded in small steps so top and bottom can be cut at the level that provides a snug fit to the mast and deck collar.
• SIMPLE INSTALLATION - Boot may be installed on stepped masts by cutting one side and glue together with enclosed adhesive. Secure top and bottom of boot with stainless steel hose clamps (not included.) Installation instructions are included in each kit.
• USAMADE GUARANTEE: If you don't absolutely love your new mast boot, contact us right away and we'll make it right!

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At USAMADE we try our best to provide value and quality. Our marine and RV components provide exceptional quality that doesn't break the bank. USAMADE is a small, private company based in the United States and we are dedicated to providing our customers with top quality, American-made goods. Using industrial and military grade materials, USAMADE’s main focus is to provide high-quality products that make your life easier and last as long as your boat or RV. With quality as our main goal, we are constantly pushing ourselves to design goods that reduce clutter and make your experience easy and convenient. Our products are easily mounted or installed in a cutout so you can upgrade your boat or RV yourself if you want. Cutout dimensions are included in the description. USAMADE let’s you make your boat or trailer that much more convenient and comfortable for your days on the water or on the road.

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Customers like the ease of use and performance of the mast boot. They mention that it's fairly easy to install and works great.

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Customers find the mast boot easy to install and work with. They say the installation of the mast went well and looks neat.

"...I installation of the mast boot went well , looks neat, and is water tight...." Read more

" Easy instalation ! Very pleased with the results" Read more

"Needed to replace our old mast boot. This was fairly easy to install , just take your time measuring before cutting...." Read more

" Easy to work with ..." Read more

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"...If you follow the instructions, take you time, the boot will work well and look better than tape...." Read more

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Departments - MAST BOOT UNIVERSAL

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MAST BOOT UNIVERSAL

Universal Mast Boot. Made of extremely flexible UV resistant vinyl. Designed to fit a number of sizes of mast and deck collars of the same basic shape. Molded in small steps so top and bottom can be cut at the level that provides a snug fit to the mast and the deck collar. Boot may be installed on stepped mast by cutting one side and glue together with the included adhesive. Secure the top and bottom with stainless steel hose clamps. Complete installation instructions are included with each kit.

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Catalina 36/375 International Association

You are here, mast collar and boot.

Hello folks.  My Catalina 36 has a boot that needs to be replaced. I plan to contact The Rigging Company for a replacement boot.  Any suggestions on the proper tape?   Also, the mast collar does not appear to have a way to attach fairleads/turning blocks/etc. in order to run lines down  the mast and then to the cockpit.  I have not noticed any aftermarket mast collars specifically for a Catalina 36.  Does anyone have a suggestion?  I wanted to do this work without removing the mast.  Is this feasible?  

Thank you for any and all assistance.  Have a super day!

Skip Kuzel S/V Trilogy, Catalina 36, Mark 1 Hull #53 Pass Christian, MS

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The boot is easy.  Go to this link:   Mast Boot C-34, C-36, C-42 Keel Stepped Mast (catalinadirect.com)  or  Mast Boot C-34, C-36 Keel Stepped Mast, C-38 (catalinadirect.com)

The second question, can you add attachment points to the mast collar?  The answer is yes, but a little complicated.  First the mast must be removed and the collar removed and drilled with a countersink on the bottom side to use the collar pin:   Mast Collar Pin, C-34 & C-36 (catalinadirect.com)   Please note:  the pre-drilled new mast collar is no longer available.  The photo does show where the pins were intended to go.  I did remove my mast collar and took it to a machine shop with a mast collar pin.  They added the two aft holes.

Shown with the pin is the block used to bring the lines down.  As you don't have that step up, you probably do not have the deck turning blocks.  You're boat is a very early model, the deck hardware is missing.  Once the blocks are added to the mast collar, turning blocks are mounted on the deck to route the lines aft.  One such block is:   Deck Organizer Ball Bearing Quad 2-1/2"Cntr to Cntr (catalinadirect.com)

A large but very worthwhile project.  We have brought all lines including the reefing lines (tack & clew) aft.  In our advanced years, we no longer need leave the cockpit to go on deck in rough weather to reef the main.

Good luck,  

Lou Bruska Sojourn 1985 C-36 Mk-I TR #495 Eldean Shipyard Lake Macatawa (Holland, MI) Lake Michigan [email protected]

my advice would be: do a proper job, forget about tape solutions, pull the mast, replace for a proper new one and you have fun and no worries the next years.

we faced similar situation when we bought our C36

I ordered a new boot at CatalinaDirect, part number A8226.

pulling the mast is not a big thing, fitting the new boot is an easy thing to do. just put the new boot in hot water prior sliding it on.

a good opportunity also to check other parts of the mast which are normally out-of-reach and which might need some live now and then as well.

Durk Nijdam S/V "SILER" Catalina 36MKII - 2001 / hullnr. 2013 Stavoren - Holland

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