Arpex Review - Lateral Plan (update)

The sailing capability of Arpex is determined by the sailplan and lateral underwater plan, like any other sailboat. Arpex has never had never in mind to explore great competitive advantages, nor was it designed to sail regatas at all. Even if, I wouldn't mind to do so. I have sailed against monohulls, and had a creditable result. And Arpex has sailed at nice speeds, as shown in this video, as of 1 minute and 10seconds... But that was not in my mind, so I didn't care about measurements, or classes, or whatever. I cared about simplicity of construction and ease of  handling during operation. I was designing a boat that should be comfortable, and easy to sail. And it should be unique, and different.

For the propulsion, I choose a wharram style softwing sail, with a wooden, hollow, round mast. A sturdy rig. It survived the failure of a shroud, with injuries, but it is now stronger than ever. The mast is keel stepped, which gave enough support to save the mast, when the shroud broke, in 20 knots of wind. Acknowledging that my configuration was different that the Tikis, on which this rigging is usually used on, with its wide beam, to serve as a wide traveller, I added a boom to the mainsail. I also produced a slightly longer gaff, to optimize sail area. And I built it lighter than specified.

The lateral plan is also conservative. I wanted structural stiffness, ease of construction, and directional stability, and forgivingness. I am sure, that a deep daggerboard would provide better upwind performance. However, the construction would be a nightmare, not to speak of the structural implications. Therefore I settled for a compromise.

The keel draughts a max 80cm. I was looking for the possibility to come right close to the beach, and actually beach the boat. The keel is built of solid wood, in layers. It is fixed with stainless bar, and screws. The wood is protected by fiberglass and epoxi.

I am happy with how the boat sails. I love its directional stability when sailing. I can leave the helm unassisted for long periods, and movements of the boat are very predictable. In this concern, Arpex is a very safe boat too. And I can single handedly operate the boat, without sweat.

But this comes to no penalty in the regards of maneuverability. Arpex reacts well to its helm. However, you do need to be in motion. As any multi, Arpex is a dog to steer in close quarters, at low speeds. You do have to act with foresight. On the other hand, since the boat is light, and easy to move about, One can fend off easily, in case of a close, drifting encounter. It has happened, and it is documented in videos that I have posted. I will admit it, but I will not link to it, though. The rudder is a wooden blade, manually shaped to form.

Another interesting point regarding the handling, is that when steering under power, you do have to take into account, that the engine is not central, nor in line with the rudder. So, certain movement can be cumbersome to perform, specially if a breeze is blowing, and windage is an issue. In this case, however, it is easy to help the boat, by using the engine to steer together with the helm. By doing this, I can maneuver without problems.

Rio de Janeiro: Afternoon on the Bay - 2018

Arpex Review - Upwind Performance

Here is an objective analysis of Arpex'es Upwind performance. The graphic analysis is focussed o that specific item of performance, because it represents a benchmark, which anyone can relate to. Even though, I believe that it is not the most favorable scale for Arpex.

I do like to record parts of my sailing afternoons on video. Generally, I try to equip my videos with information about tide and wind conditions, which is very useful for posterior analysis. Which is the whole idea why I do it, in the first place. So, I am pleased with that.

By using the plotted course of a few upwind leg as a reference, copied for the recent video "Bumpy Ride", I get to the conclusion that Arpex tacks through approximately 110 degrees - which makes 55 degrees for each leg, in theory. However, I suppose there is a positive bias towards the tack when the ama is to windward.  So, maybe it is more like 52 vs. 58 degrees.  ... I might produce more data on that in the future.

Optimizations could improve the sailing angle to at least 105 degrees, maybe 100. A better jib could produce that, along with improvement on the sheeting points.  And, I admit, that I am not a very skilled helmsman. I suppose that a more skilled person could improve those figures.

But Arpex loves to bear off a bit, and see the water rush by in a quicker pace. The top speed recorded was 11,9 knots. Speeds of 13 to 14, or 15 knots seem feasible in stronger winds. But spped of 8-9 knots are quite usual during our average conditions.

The sailing movement of Arpex is very agreeable. There is no hobbyhorsing, or other vicious movement. Also behaviour in waves is pleasant,I suppose the difference in hull length and volume has a positive effect.