Latest Blog Posts

Identifying A Lewmar Hatch

What’s the Difference Between Lewmar Hatches?

Lewmar produced Low profile and Medium profile hatches

These two variants look alike but have differing hatch frame thicknesses.

  • Low profile hatch lids are 22mm thick
  • Medium profile hatch lids are 27mm thick

Distinguishing between Mk 1 and Mk 2 hatches

In the last half of 2000, Lewmar changes the manufacturing specs on both their Low and Medium profile hatches If you are sure that your hatch was constructed before or after this time then you should know which of these hatches you have.

You can always check to make sure.

Look at the Roll pins.  A Mk 1 hatches will have a visible roll pin on the underside of the lid near the hinge

Mk 2 hatches do not.

Lens code.  Look for the lens code located under the seal. It is embossed on the underside of the lid next to the handle. You do have to pull back the seal to expose the lens code. Call us if you have toruble locating the lense code.

Hatch and Portlight “Leak Stop Kits”

Year after year I get the same question….

“My hatch is fine, it just drips occasionally.  I don’t want to go to the trouble of sending it in for a complete service.  What other options do I have?”

You asked, and we listened…….

Our product development team proudly introduces “Lewmar Leak Stop Kits” .


We have put together the correct parts to eliminate water infiltration through handles and friction caps for Lewmar Hatches and Portlights manufactured since the 1980’s. These kits have the handle seals, friction seals and lubricant you need to stop those annoying drips.  All materials are the same “marine” quality we use in the rebuilding process at the factory.

You may ask: What size kit do I need? NO PROBLEM…. If you are not sure send us a picture of your hatch and we will link you to the correct part.

These kits were introduced originally at the Newport and Annapolis boat shows to rave reviews.  They are flying off the shelves.  Don’t miss out; get a few sets for your spares / offshore kit now!

HatchMasters is making boating safer one hatch at a time.


Acrylic vs. Polycarbonate

I spend inordinate amounts of time discussing the pros and cons of acrylic and polycarbonate.  In so much as I would like to bring some clarity to this issue.  Please consider the following:

  • All major hatch, portlight, and window manufacturers use Acrylic in offshore / bluewater marine products.
  • Acrylic is more scratch resistant than standard (9034) polycarbonate.
  • Acrylic is significantly more durable when exposed to Ultra Violet radiation (sunlight).
  • Acrylic is less expensive than Polycarbonate.

Don’t misunderstand my preference for acrylic. I buy, use and sell a significant amount of both products and each has its application. In my humble opinion Acrylic is more durable, versatile and cost effective in the hands of a skilled craftsman than polycarbonate.

Additional considerations may include polycarbonate with UV and scratch resistant coatings. While these products are heavily promoted by several manufacturers and carry 5, 10 even 15 year warranties the following information has been reported in “real life” applications:

  • Polycarbonate is impact resistant. When it’s new it is almost impossible to break.
  • Small quantities (less than a 4 by 8) in gauges over 1/8th inch are difficult to find in the UV- scratch resistant grades.
  • Colors are limited. Only two standards (gray and bronze). Try and find anything thicker than 1/4 in UV/ scratch resistant!
  • Polycarbonate foreshortens when subject to static or dynamic loads. What this means is if you replace your hatch lens with polycarb, seal it and then step on it the ductile material will deflect (bow) in the center. One of two things may happen. 1st you will surely break the watertight seal, 2nd you may end up with a leg in your salon.
  • As for the warranty: The original owner is warranted against failure subject to the material being submitted to the distributor for evaluation with the original invoice subject to actual replacement cost at the time of  purchase. I guess this means they sell you a new square of material and apply the old payment to the new cost. How about the labor to fabricate the part, install it and sealant? Why take the chance?

Polycarbonate is a great material; The US Air force uses it for fighter canopies! I sell Polycarb to the USCG and US Navy. Remember they don’t mind using it because we are paying to replace it every three years.
Both Acrylic and Polycarbonate have specific uses and installation requirements.

Cast Acrylic (of a specific thickness) is in accordance with CE and ABYC guidelines, and installed on virtually all of the big blue- water sail boats produced on both sides of the pond. Polycarbonate is commonly used as a replacement due to its ease of fabrication and incredible initial strength. The USCG and USN require Polycarbonate on their vessels but they also have a preventative maintenance cycle of 36 to 42 months for change out. My Tax dollars at work…

Due to its ductility Polycarbonate it is more challenging to install. I have seen Sika Flex 295UV with primer and Dow 795 both mentioned. I use and recommend both. Dont go over 4 ft continuous length with a fixed portlight. Remember the coefficient of thermal expansion for Acrylic and Polycarbonate is in the neighborhood of .000039 per inch per degree F. That means an 8ft plastic port will expand and contract up to 1/2 of an inch from the coldest day in Feb to the hottest day in summer. WOW!! Compartmentalize the job. It will be easier to install and less prone to leaks.

Never ever bolt a plastic portlight in place. Screws are fine to hold a lens till the adhesive cures. Take them out asap and fill the holes with the aforementioned products. Both of these products are rated at 700 + percent elongation before tear. Strong flexible and UV resistant.

Been to a boat show lately? Seen any screws? Glass is good so long as your boat does not twist or torque. Show me a fiberglass boat that does not twist and I will show you a cocktail barge tied to the dock”.



This subject always cracks me up…

Listen guys……. crazing in acrylic is caused by either thermal or mechanical stresses imparted during production, transport, manufacture or in use.

Acid rain,Ultra – Violet degradation, Windex or the boat detailer’s magic deck cleaner (to name a few) accelerate the process.

Once something is crazed it is significantly weaker than the same part in factory OEM condition.

How do you stop it? Make Sunbrella covers (not vinyl backed Sunbrella!!). Use cleaners specifically designed for Acrylic.

How do you repair it? You don’t.

We have all seen the lotions and potions sold at boat shows to cure everything from warts to your crazed hatches. You still have the warts don’t you?

You can follow the military specification procedures from the USAF/USN and sand the lens until you are below the crazed line, sand again in successive grits and buff with 4 or 5 different compounds until clear again. Remember annealing? Yea…. you need to get the mechanical and thermal stress you just put in with the sanding and polishing out! Well at 170 degrees F for 12 hours (1/2 inch acrylic) and cool down at the same rate, oh and now you’ve found the seal puddled in the bottom of your wife’s oven and the parakeet is dead from the MMA vapor being out gassed during the process. New seal, new oven, new wife?

By the time you have completed this repair you could have purchased two hatches, thrown one overboard and had the most expensive yard in the States install the second with the gold plated rag-surcharge and be ahead of the game.

I repair thousands of hatches every year. I know replacing the lens is an option but repairing the crazing with potions or flames is not realistic.

Let me know if you want some pictures of really crazed hatches. I have seen every make and model you could imagine.

I would like to help. But even the Hatchmasters can’t make crazing disappear. (yet)


Which Sealant to Use

I hear the question as to which sealant to use when bonding Acrylic or Polycarbonate to aluminum, stainless or FRP over and over and over…..

Well here goes… The only three adhesives I would consider using are Sika Flex 295 UV with the primer, GE SG-4000, and Dow 795. Using the correct adhesive is only 1/2 the battle. Do not apply the sealants below 50 degrees F. The temperature must maintain at least 50 degrees F during the entire 21 day cure cycle. Cut this corner and your finished before you start. Preparation of the bond area is also very, very important. DO NOT TOUCH THE BOND AREA WITH YOUR BARE HANDS! Contamination from the dirt and skin oils will make a solid cure impossible. You may clean the FRP and metal with acetone to prep the area but if you touch the Lexan or Plexiglas with harsh solvents you will ruin the portlight. A 50/50 mix of isopropal alcohol and distilled water will work well to clean the plastic if needed. Remember that clean enough is not clean enough.

Lewmar SuperHatch Hinge Kits

Re-introducing the Lewmar Superhatch hinge repair kit.

This kit will eliminate the old style Superhatch from falling and whacking your hand.

Kit contains new followers, snubbers, hinge pins and washers.

Plenty in stock.  We made a boatload. Call for more information or see the Lewmar section of the web site to place an order.

You asked and we listened.  The HatchMasters Product development team strikes again. !