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Front Hatch Replacement

Replacing the front hatch on my J29 sailboat BlackJack has been on the list for a few years. The old foredeck hatch was made by Bomar. and it was showing its age.

The hatch had these spring-loaded latches that were horn-shaped. We used to launch the spinnaker out of the forehatch back in the day, and these horns would snag the chute. So the horns were removed.

I must confess that I never put those horns back on. BlackJack sat unlocked for the last 10 years or so. Good thing no one ever goes around the marina trying to open hatches on boats.

The hatch never leaked, so I admit my desire to replace the hatch was just for the looks. I have restrained myself from getting into cosmetic projects because there are many important things like lifeline needed work.

Then one day, I got a promotional email from They were having a sale on Lewmar hatches. So I did the right thing and ordered myself a brand new Lewmar Size 60 Medium Profile Ocean Hatch.

Yeah yeah, it’s just for looks, but why not? Replacing the hatch is an afternoon job at best. I’ll get right back on other important projects.

Boy, was I wrong.

New hatch (towards the bow) vs Old hatch

Removing the Old Hatch

Removing the old hatch entails removing the mounting screws and prying the hatch off of the deck.

Simple enough. Let’s get right to it, shall we?

Right away, I ran into trouble. Once I removed the screws, I found the old hatch stuck on impossibly tight. Whoever mounted the hatch used a whole lot of silicon. I tried wedging a flat blade screwdriver under the hatch lip, but this proved impossible. I then used an oscillating tool, which made small progress and a whole lot of mess.

Silicon dust everywhere

Once there was an opening, however, I was able to take two flat blade screwdrivers, wedge them in alternately, walking them along the edges. This sounds simple but in reality, it took a lot of pounding away at the screwdrivers. I was doing this on a quiet, peaceful Sunday morning at the marina, too.

After considerable effort, with the crackles of silicon peeling off, the hatch finally came off.

Who has a hammer on a boat? Vice grip does nicely though.

Problems Under the Hatch

I then discovered more problems.

First, this was not the original hatch installation. With the old hatch removed, there were two sets of old mounting holes. Mounting holes for the new hatch would make it three sets, and they all don’t line up. Mounting lip would look like Swiss Cheese with all these holes, not to mention possible water intrusion. I need to fill these old holes with epoxy.

Also, Lewmar Ocean Hatch frame is smaller than the old hatch, and some of these old holes would show when I mount the new hatch. These holes need to be covered with Gelcoat as well. Basically, I need to re-finish the lip area where hatch mounts.

The second issue was, whoever installed the old hatch decided to widen the opening. They ground away Gelcoat and even fiberglass on two sides. This really annoyed me at first since this would create a big opening for water to get into the deck core.

On closer inspection, however, I could see that the core in the deck lip – the raised white part – is not balsa. It’s some filler mixed with epoxy or vinyl ester and it’s waterproof.

Still, this made it a bit challenging to mount the new hatch, as I had to center the hatch precisely in the opening.

Three sets (two old and one new) of mounting holes. None of them lined up.

Preparing to Mount the New Hatch

Removing the old hatch was hard, but the prep work took the longest.

First, we had to remove tons of silicon still stuck to the deck lip. This was very tedious. Fortunately, Mari took time off from her busy Tennis schedule and helped. It was good to have help.

Mari scraping away

Her patience quickly ran out, however.

Mari had enough.

Once we managed to scrape off all the silicon, I filled all the old mounting holes with West Systems epoxy. Once the epoxy is cured, each hole was sanded lightly with a Dremel tool and wiped with Acetone. The old holes were then covered with Gelcoat that I color matched.

There are two important facts about Gelcoat. First, color-matching Gelcoat is an art. Second, I do not possess much in the way of artistic talent. I ended up discarding a few batches of Gelcoat because I kept getting completely the wrong color. My hats are off to those who have mastered this art.

Once Gelcoat cured, lots of sanding took place. There were so many holes that received Gelcoat. The whole white Gelcoat was wet sanded and polished.

The hatch mounting lip looked normal again.

Mounting Lewmar Ocean Hatch

The holes for the new hatch were drilled then potted with epoxy. I then drilled the mounting holes in the epoxy. I was able to get all the holes to line up with the center of filled epoxy more or less, which I was quite happy about.

Mounting screws for the flange are self-tapped into the lip except for the 4 holes around the hinge that are through-bolted. I have hundreds of stainless fasteners but it’s never the right size. This required a quick trip to WestMarine.

At this point, we were finally ready to mount the hatch.

After dry-fitting and making sure everything fits, I put down masking tape, then put dabs of 3M 4000 Marine Adhesive Sealant on the hatch flange and the deck lip.

Then I lowered and mounted the hatch, making sure sealant gets squeed out from everywhere. I did remember that the sealant will get on everything. So I kept changing gloves.

New hatch mounted, celebratory dancing ensued

And now, after spending two weekends on what was supposed to be an afternoon project, I have a shiny new hatch installed. Properly too. Oh, and it even locks.

Below is before/after picture. With the new hatch, BlackJack looks different. I have to say, I never really liked the high profile look of the old hatch. On the other hand, I’m finding myself not quite used to the rounder profile of the Lewmar Ocean hatch.

I think it’ll grow on me, though.

BlackJack with old hatch.
BlackJack with new hatch

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