Blue Water Essentials in a Small Cruiser – Passage preparations for the Vivacity 20
The Hull: Part 1
by Dave Chamberlain
Some would contend, and maybe rightly, that preparing a twenty-foot coastal cruiser for an ocean passage is ludicrous. My wonderful wife, Eva, might have, at one time, shared that opinion. I believe, however, any owner of a small twin-keeler can modify her into a solid and safe blue-water vessel. The most vulnerable feature of trailerable cruisers is the swing keel or fin keel. These flimsy appendages were not designed to withstand the rigors of a full gale for days on end. A twin-keeler is different. It is built to completely support the hull’s weight, not only in the water but out of the water as well. How many trailerables could bounce up the highway at 55 MPH with the entire weight of the dry hull falling only on the keel for support? Most twin-keelers (especially those made for trailering) are more than strong enough for passage-making.
Permanent Internal Flotation
What else is needed to make the hull truly seaworthy? Self-rescuing capability. The owner of a small cruiser must accept the fact that his vessel is also his life raft. He does not rely on a flexing, vulnerable rubber raft. The small cruiser’s best defense is to have permanent internal flotation situated in such a way that if the hull is holed or in some other way compromised, she will float only three to five inches above the waterline. Even if the cabin gets fully flooded, one can find it dry in the cockpit, while areas repaired with glass and underwater epoxy cure. This type of security is realized by filling every square inch of the hull not used for storage or living, with two-part polyurethane foam. The foam greatly increases the strength of the hull below the waterline; and since the foam has incredible adhesion, even if the hull is stove in, it will not leak. Well, not much, anyway.
After this project was completed on “mini” in preparation for her 2,500 mile Pacific cruise, some friends and I sailed south San Diego bay and pulled out the two-inch knotmeter plug from the floor. Water came pouring into the cabin like a town square fountain while we sailed merrily along. When the water reached the level of the quarter berths, the incoming water stopped. We were still sailing along with an (almost) dry cockpit and neighboring sailboats never knew we had a fully flooded cabin. We hove to, put the plug back in and bailed as fast as we could. In thirty-one minutes the water was out. Success!
Locking Locker Lids
There are ten inside compartments of my year and model of the Vivacity 20. There are seven under the four berths and three on the floor. Each of the berth compartments must have two mini bulkheads, one fore, and one aft, glassed in. These small, plywood mini bulkheads keep the foam from expanding into the storage area. When the project is done, you will not be able to find any exposed foam. Each small bulkhead will be a little different shape and size, realized by trial and error using cardboard templates which are easily trimmed with scissors. Once your cardboard bulkhead fits nice and tight, you will stencil it onto a sheet of quarter-inch, exterior grade plywood.
Cut it out with a saber saw (use a blade designed for metal because it cuts much more smoothly), sand clean, check for fit, then lay on two coats of epoxy.
Install and glass it in place using 2-inch fiberglass seam tape. On “mini” I made the storage compartments about two to three inches larger than the hatch covers. This allows for more storage as well as room for a latching mechanism needed to secure the hatch in case of a knock-down. Now you have nice storage areas with the little bulkheads set in as dams to hold back the expanding foam when it is poured into the unused portions of the hull.
I used a doorknob hole bit in an electric drill to open two-inch holes wherever I could find a void where I could pour in the two-part polyurethane foam. On the V-20 you can pour foam under the cockpit, under the port storage area beneath the counter, under the sink, fill up the area underneath the sampan post and in all the structural members between the floorboards. If your boat has air-tight compartments for floatation, FILL THEM WITH FOAM.
Purchase the polyurethane foam in two-gallon kits at better fiberglass retailers. Pour equal amounts of parts A and B into a disposable container. Stir hard and fast. The brand I used eventually turned a jet black color. Stir another two to three seconds, then pour through the hole. Start with small batches so you can get the feel of how much the foam expands. Most brands reach 95% of the expanded size within twenty minutes. Make sure the hole you’ve made is the deepest part of the cavity. There must be a vent or vents to allow the excess foam to expand. I found a single drilled hole to be adequate. Without venting areas, the foam will expand and break something. It’s powerful stuff. Read and follow the instructions. I was able to reinsert the plug that was drilled out as the foam expanded up and supported it. A little Bondo, sanded and painted, and no one would ever know there was a hole.
Each locker must have a hatch cover that can be locked down. Don’t skip this step. All items in a locker must stay there in case of a knockdown. I converted the existing covers per diagram. Your battery tie downs must be incredibly strong. One of the most dangerous aspects of a knock-down or roll over are batteries, the tool box or tin cans getting loose from their lockers.
When I acquired my Vivacity, the fiberglass box channel, inside the cabin, which supports the mast step and extends to both the port and starboards sheer was broken. It had pulled away from the hull.
To fix it, I jacked up the cabin right under the mast step and refiberglassed (many layers) where it had separated just forward of both the port and starboard storage shelf. I figured this must be a weak link, so I installed a compression post under the mast step. I sail without the post unless I anticipate heavy seas. I made my compression post from an oar. The post must extend to the floor right down to the hull. There should be a multi-layered plywood (marine grade) pad to receive the compression post on the hull and under the deck to spread out the stress.
With the completion of these three projects, you are well on your way toward increasing the seaworthiness of your twin-keeler or small cruiser. Work projects and upgrades accomplished by ourselves greatly increase the emotional attachments and sense of ownership we have with our vessel. After finishing “mini” for her Hawaiian adventure, I’ve never yearned for another boat. This has made Eva very happy.