Friday, August 30, 2013

New Bottom

Finisterra was hauled out of the water the day before yesterday to get fresh bottom paint and have some other minor work done. This is the first time I've had a chance to inspect the bottom carefully and I was pleased to find it in generally good shape. The bottom paint is still in reasonably good condition except for a few small spots on the keel where the paint has been rubbed off. The painters will sand and prime those areas and she'll receive two coats of Pettit Trinidad before she goes back in the water next week.
Beneteau 423 Deep Keel

A couple of observations regarding the design of the boat that are not apparent when she's in the water:
The keel is made of cast iron and weighs about 5,569 pounds. My rough calculations indicate that about 40% of its weight is in the bulb at the bottom of the keel. The bulb is about 16" wide at its thickest and fairs into a very thin fin section. I took some basic dimensions and discovered that the fin is about 3" thick at the thickest point with a chord length of 64", for a thickness ratio of  .047 or 4.7%.  The top 8 or 10 inches of the fin fair out to a beefy and wide hull/keel joint. So, if we disregard the bulb and the thickened area at the hull/keel joint, the actual lift generating part of the keel is about 36" high by 64" long, with a thickness ratio of 4.7% and an aspect ratio of .56. I won't go into a technical discussion of keel design here but I would love to hear the designer explain his reasoning behind these numbers.  It would have been a simple matter to design a much more efficient keel using the same amount of material and draft for exactly the same amount of money, so I wonder what the designer was thinking when he or she designed it.
Cast iron fin keel. 

Note how thin this keel is. Racing keels have thickness ratios roughly twice the 4.7% of this one.

So what conditions would this keel work best under? Well, it'll never generate much lift on the upwind legs and it sports too much wetted surface and parasitic drag to be much good in light air. It will probably work best broad reaching and running in medium conditions. Our experience sailing the boat certainly bears that out. With all that said, if any of you B423 owners out there want to improve your boat's performance, swapping out the keel would be a quick and effective way to go.

How about the rudder? There have been times when we've pressed the boat pretty hard on a reach and the spade rudder has proven to be up to the task of steering her in a straight line. Of course the boat can be pushed hard enough to round up in a breeze but it gives plenty of warning and it rounds up in a predictable manner. There is nothing special about the shape of the rudder. It is a bit over-balanced for my taste, meaning that under power if you let go of the wheel, the rudder will slam  hard over to port or starboard quickly. I'm not pleased by this, but the excess "balance" of the rudder makes helm loads pretty minimal when under sail. This means that you can sail the boat with little pressure on the wheel and the autopilot never has to work very hard under sail. I suppose this is a good trade-off, but I prefer a perfectly balanced helm. The rudder stock is vertical and rides in a set of bushings. From a purely hydrodynamic point of view, a vertical stock is more efficient than a radically angled one. In most boats the upper rudder bearing or bushing is mounted to the underside of the deck but Beneteau has chosen to build the entire rudder support system into the hull only. On my last boat, a Beneteau 36s7,  this structure was made of a fiberglass cone about 36" high glassed to the hull with the upper bearing mounted at the top of it. It was a bit disconcerting to see the top of  the cone moving around as the boat sailed in anything other than flat seas. Finisterra has a similar arrangement except that the cone has been replaced by a set of longitudinal and transverse bulkheads which appear to do a better job of resolving all the loads imparted by the rudder. At least I have not been able to see any movement of the assembly while underway. I can't say I'm a big fan of this method for securing the rudder stock but from a purely structural point of view it works. The main disadvantage is that this arrangement is heavy and takes up a lot of space.

Slipstream Stainless Steel Propeller

Three blade folding prop is a vast improvement over the standard fixed prop. Notice the small collar type zinc. In our harbor these things need replacement about every six weeks. 

The hull shape itself is very respectable. It's not a particularly beamy boat and the waterlines forward are finer than I expected, while the stern sections are fairly broad. the U-shaped sections forward are about what you'd expect and there is no doubt that the 423 will pound a bit when motoring into a head sea. Once again, I think that's a reasonable trade-off for good performance reaching and running.

I was glad to find minimal play in the rudder when I grabbed hold of it and pushed from side to side. My guesstimate is about 1/8 inch in each direction. Overall, I think the hull and appendages are in good shape for our upcoming voyage. The fresh bottom paint should last a couple of years in the tropics.

Mounting the instruments in the cockpit required moving the rope hangers outboard. 

I mounted instrument brackets in the companionway too. I plan to build a removable seat that will fit in the companionway recess. It's a perfect place to be on cold or rainy watches. 

While the boat is out of the water I replaced the speed and depth sensors. Awhile back I bought a Tacktick T104 instrument package for the boat but have not been able to complete the installation of the system until the boat was hauled and I could change the sensors. Now we'll be able to use the Tackticks for speed, depth, wind, VMG, etc. By the way, out of curiosity I measured the thickness of the hull laminate in this area. Using dial calipers which I was just able to fit through the hole, it measured .66".

Sunday, August 11, 2013

Cockpit Table

I've been busy with work during the month of July so getting things done on the boat has been a challenge. But I did finally finish the new cockpit table and get the Garmin GPS installed.  We also have a new 120% genoa aboard, but haven't set it up on the furler yet. Lastly we took the liferaft and MOM unit in for servicing.

The reason for the new cockpit table is that the original one took up too much space and we got tired of it being in the way. The new arrangement works much better for actually sailing the boat and provides a place for the new GPS.

The process began with removal of the original table. The photo below shows the standard arrangement for the B423. You can see that it pretty much fills up the cockpit forward of the steering pedestal. It is fitted with large drop-leaves that make for a very spacious dining table when they are deployed and for many B423 owners it's a good arrangement.
The lid fits loosely on the table and encloses a deep stowage bin. Notice the slip pin hinges for the drop-leaves.  

Plenty of room with the table removed

Removing the table reveals the spaciousness of the cockpit. I filled in the holes left by the mounting bolts. Later I installed a teak foot rest which concealed them. The table legs are nicely made of stainless steel and are plenty strong so I kept them for use on the new table.
Table base incorporates a solid, if slippery footrest. The blue tape covers the forward hinge which had an uncanny ability to snag clothing.

The next step was to mock up the new table. I wanted it to be smaller than the original table, incorporate the new GPS and provide solid hand-holds. I took a template off the forward side of the pedestal and entered those dimensions into the computer because I wanted the new table to follow the contours of the pedestal. Then I played around with different shapes until I had something that looked like it would work. I made a mockup out of particle board and check fitted it.

Particle board mockup. 

The new shape looked good, but the original table leg assembly was not tall enough. I wanted the table to be high enough that we could see the new GPS even when standing at the wheel. So while the leg assembly was in the shop getting modified I laminated up a mahogany riser and fabricated the table itself out of 3/4" StarBoard.

The mahogany riser puts the table at a convenient height. The post that the GPS is mounted on can be adjusted for height and it swivels. The cable is routed down through the post and fed into the starboard table leg. From there it passes through the deck and into the aft cabin. 

With the GPS mounted high enough for good visibility from the helm, it was too high to be convenient when sitting in the forward part of the cockpit, which is why I incorporated a pedestal that can be adjusted higher or lower and swivel for good visibility from anywhere in the cockpit. When we're at sea, we almost never stand or sit at the helm. When you're on watch alone, the autopilot will always do a better job of steering the boat than a human over the span of an entire watch. The best place to stand watch is in the shelter of the dodger. On the Beneteau 423 that presents a problem because all of the instrumentation and controls are on the "dashboard" at the helm. The new GPS solves the navigational aspect of the problem and it will display AIS information as well. The handheld remote for the autopilot substitutes for the controller at the helm. The new TackTick sailing instruments are wireless and the displays can be located anywhere. So with this system in place we can navigate and control the boat from the most comfortable spot in the cockpit. This gets real important when you're punching into a head sea on the midnight watch and you're the only person on deck for three hours on a windy and moonless night.

On the left is a 2011 Santa Margherita Pinot Grigio, to the right is a 2009 Cakebread Cabernet.

Once the unit was installed we had to check fit the drink holders. They worked like a champ! I have been planning to add a fold-down dining table which would be attached to table leg assembly but for now, we're pretty pleased with the current arrangement.

                                                                 The Rescue Pod

Switlik Rescue Pod 4
Switlik refers to it as an "Emergency Floatation System" rated for 4 people. It would be extremely cozy for four, but reasonable for two.

Finisterra has a Switlik Rescue Pod for a liferaft, which is fine for coastal cruising in the temperate and tropical regions where the Finisterra will be traveling. It was time for a checkup so I took it to Avalon Rafts in Wilmington, California. Everyone who owns a raft or races offshore has taken a Safety At Sea course and seen raft deployment demonstrations, so you have a general idea of how they work and how they are equipped. But few of us have deployed our own raft, so we hung around and went through every detail of our little pod. It was something of an eye opener to see exactly how it works, what happens when things go wrong, and what the equipment bag really has in it. It has caused me to revise the equipment and supplies we carry in our ditch bag and I feel a lot more prepared in case we ever have to deploy the raft in a real emergency. If you plan to do any truly offshore work, one look at the Pod when it's deployed will convince you to opt for a real liferaft.

The Pod is, as you can see in the photos, basically a flat disc. That means that in has a 50% chance of inflating upside down. It has a righting line across the bottom, so it can be righted, but if you have a Pod, keep in mind that the first thing you may be required to do once you've launched it, is to get in the water and pull the thing upright. It looked pretty easy in the comfort of Avalon's shop. It might be a different story in 15 foot seas and 40 knots of wind.

I snapped the photos below with my phone so they are not very good quality, but you can see fairly well what the rescue pod is like.

This is how the raft looks after it's hit the water and inflated. The CO2 canister is in the background. It normally remains attached to the raft. The pressure relief valve is the donut shaped part in the foreground. The drogue or sea anchor is the white thing on the left. Equipment visible inside the raft is stored in the equipment bag.

The person standing in the background provides a good indication of the size of the Pod. This is a single chamber raft, which means that if it is punctured, it turns into a large trash bag pretty quickly. So be sure that you throw it clear of any sharp objects and try not to accidentally stab it while getting aboard. The unit comes with a repair kit, suitable for fixing two holes. Unfortunately the instructions are printed on a little piece of paper and carefully packaged with the kit in a small plastic bag. So be sure that when you do get that puncture, you're in a clean, dry place and have plenty of time and good lighting so you can read the instructions, which call for cutting the hole large enough to slip one part of the "clamshell" inside the the air chamber then clamping the other half to it. Stay calm while the air is whistling out of the hole and you're reading those instructions.

Standard rescue pod equipment include a surprisingly effective manual pump, combination strobe and flashlight, puncture repair kit (in the plastic bag), and a relief valve cap (the white thing below the repair kit).
I'll post our revised ditch bag equipment list in another day or two.