Hardtop and Arch

Catamaran Hardtop and Arch

We decided
to add an arch and hardtop to our cruising catamaran after five years of sailing
on our cat with no protection in the cockpit. We were inspeired by the arch
that is on a Manta 40 catamaran. During the major renovations we did in the
summer 2005, we hired Roland Irion, a custom stainless fabricator based in Langley,
a suburb of Vancouver, to build our stainless steel arch. Roland’s work is impeccable,
and very durable. At the same time, he built us great railings for the aft hulls
and aft cockpit.

Here is our article that appeared in the July 2007 Issue of Multihulls Magazine:

A Hardhat for the Working Catamaran

One of the great things about building your own boat is that you never are
really finished. Our latest “one last thing” was inspired when I
saw a Manta 40 catamaran sail by one day with its fabulous arch and hardtop.
I said to my wife Carllie, “We have to have one of those!” She thought
I meant the boat, but really I just wanted the arch and hardtop (okay maybe
I wanted the boat a teeny bit).

Light Wave with no arch

Later that night back at home, my mind raced with ideas and images. I began
researching all the various flavors of arches through my back issues of Multihulls
Magazine and the web so that I could add some practical ideas to my vision.

THE PLAN We finally came up with the following list of features
we wanted in our custom arch and hardtop:

  1. High quality, very sturdy stainless arch that will support a large hardtop.
  2. Arch is stiff enough to support the loads of the main sheet relocated to
    attach onto the hardtop.
  3. Arch and hardtop support removable sun awnings for the entire cockpit and
    aft hulls.
  4. Arch includes brackets to hold our folded Porta-Bote, and provides brackets
    or supports for the barbeque, fishing rod and downrigger.
  5. Arch provides an aft rail as well as additional handrails around the cockpit.
  6. Hardtop is fabricated with foam-cored fiberglass and protects the whole
  7. Hardtop houses solar panels.
  8. Hardtop also provides built-in water catchment system.
  9. And last but not least, hardtop provides a super diving platform!

The final product!

HOW WE DID IT We didn’t go right to the final arch and
hardtop, but took a baby step when I made a small four foot by four foot mini-hardtop
that just covered the area outside the bridgedeck door. We used this prototype
for 18 months, and found that even this little 16 square foot area provided
significant shade from the sun and the rain prevalent on the west coast of British

Our mini test arch

COMMITTED With our planned July 2006 trip to Mexico and points
further south only a year away, it was time to make the full arch and a 50 square
foot hardtop. We hauled the boat in late May 2005, aiming to complete the work
in four weeks. Like all boat projects it quickly stretched into eight. Early
in the year I contacted a local stainless specialist, Roland Irion, who does
fabulous work and was prepared to work with me on my project.

One thing we found is that it is virtually impossible to come up with measurements
and design of an arch (or any stainless addition for that matter) on paper and
hope to have the arch correctly fabricated to fit exactly in just one go. To
get an exact fit you have to make a mockup out of wood to make sure that all
the clearances, angles and attachment points work. Equally important, you want
to make sure that the arch-hardtop addition does not detract from the lines
and good looks of your boat. All these mockups and fittings entailed Roland
making four separate trips to the boat for the arch alone to check each step
of the construction.

We wanted to relocate the inverted vee dual mainsheet system, which currently
went right through the cockpit area, to the top of the arch to reduce the line
clutter in the cockpit. To do this we had to make the arch substantial enough
so it could handle the significant mainsheet loads. We also came up with the
idea of extending the stainless frame forward to the top of the cabin, in effect
making a “roll cage” with a total of six attachment points to the

The first step was to have Roland fabricate and bend up the basic arch without
the mounting plates, corner doublers or forward roll cage. With the basic arch
component I was able to build a mockup of the full arch using 2 x 4 lumber to
now include the forward “cage” where it would attach to the existing
bridgedeck cabin rooftop. This mockup stage was an important one, and it took
several days of fiddling to get things right.

Building the mockup

With the mockup of the arch completed, I then made a plywood mockup of the
hardtop out of thin 1/8 inch door skins and some small 1 x 2 lumber to get the
shape and coverage we wanted and to incorporate the rainwater catchment system.
This mockup was equally important as it allowed us to see how the arch would
look on the boat and to make sure there would be sufficient room to get by it
as we stepped in and out of the cockpit either moving to the foredeck or back
to the transoms.

Hardtop mockup

Underside details

I then took the mockup off the hardtop and used it to determine the dimensions
to build a basic flat panel melamine mold that we would use to glass up the
hardtop. I also took off the partial stainless arch and the wood mockup of the
forward roll bar and gave it to Roland. He was now armed with the dimensions
to start all his remaining work of stainless cutting, welding and final polishing.

While Roland took care of the stainless work, Carllie and I made the mold
for the hardtop. We decided to build the hardtop upside down, so we started
by making a flat table from 3/4 inch melamine particle board which would provided
the smooth mold surface for the top of the hardtop. We then added onto the outer
edges of the table the mold pieces for the beveled sloping cants for the outer
one foot of the hardtop.

Building the mold for the

We were now ready to do some serious ’glassing. The sweet smell of styrene
coated our nostrils and took us back to our days of building Light Wave seven
years ago. After laying the outside layer of mat and 1708 biaxial, we carefully
bonded in half-inch foam with plywood inserts for all the attachment points.
We then finished off with another layer of biaxial and mat.

Glassing with foam core

After a little struggle I was able to pop the hardtop off the mold table.
We then did some light fairing of the inside of the hardtop, flipped it over
so it was right side up, trimmed it, and then glued on the rain gutter edge.
After a couple more days of sanding, priming and painting we were all ready
for the arch.

Finished hardtop

Roland made two more trips out to the boatyard for the final fitting of the
arch and welding of the Porta-Bote, downrigger and barbecue attachments. In
mid-July with a golden sunset as the background, Roland delivered the final
super-polished arch. It was a thing of gleaming beauty. We were now ready to
mount it to the boat. Because some of the legs of the arch would be mounted
on a structural cross beam we took great care in over-drilling our holes and
filling them with epoxy plugs first. We then drilled the final mounting holes
into the epoxy plugs so no water could get into the wood of the beam.
After two days spent installing the arch, we mounted the hardtop on the arch
and again after more over-drilling, final drilled the 16 one-quarter inch holes
for the bolts that affix the hardtop to the arch.

On July 22, 2005, two months to the day after arriving in the boatyard Light
Wave went back into the water. We enjoyed the last half of the summer on weekends
and slowly installed the cockpits lights, solar panels, antennas, barbeques,
fishing rods and downrigger.

In October 2006, three months into our trip to Mexico, I finally got around
to sewing up the awnings in Santa Barbara, and since then we have enjoyed full
shade from the tropical sun.

ARE WE HAPPY? Yes! We are very happy with the results. We
honestly do not know how we lived without the arch and hardtop. It has met all
the points in our wish list. We feel like we have added a whole other room to
the boat, as the cockpit is so much more usable and enjoyable now. When sailing
we are now totally secure, with extra handholds in the cockpit. We are protected
from the harsh sun and rain, and the hardtop makes a super diving platform,
for extreme diving, that is!

Finished arch

This project is definitely do-it-yourselfer as long as you have some help
with the parts outside your normal skill range (in our case the stainless work).
The keys to the project are the step-by-step mockup of the arch and hardtop,
and hiring a proven stainless fabricator who is willing to work with you on
the details. Though this is a longer road, it will deliver better results in
terms of functionality and ensuring the arch and hardtop adds to the good looks
on the boat.

I guess this means we are finally finished our boat. Wait a minute! What’s
that over there? Look at those neat davits!

Anchored at Catalina Island

[In fact at the time of recounting this building process in late April 2007,
we have hauled out Light Wave in a boatyard at Guaymas on the Sea of Cortez.
We are working on some major improvements before we resume sailing the Sea and
then head off for our big ocean passages home to Vancouver via Hawaii. Look
for the new improved Light Wave XP (Xtra Performance) in a future edition of
Multihulls Magazine.]

More Photos of Construction Details

Solar panels

Corner reinforcing

Base mounts


Underside details