Design Brief

 The sketches have been produced around 2010 or 2011, during the construction of Arpex. The objective was to get an image of how the boat would look, once equipped with its decks and cabin. Since I didn't have detailed construction plans, I used these sketches to move forward with some design decisions. The images were produced based on actual construction site photos, which I amended with PowerPoint... :-)

I liked to produce the more artistic view, instead of precise drawings. The whole boat construction had an artistic approach, and I viewed the boat itself as an object much like the mobiles which I like to build. And in fact, there are many similarities in the sense of balance, structure, and movement.

Performance Review - Ease of Handling

 Performance is generally expressed in numbers, like speed and sailing angles. But safety and ease of handling is also an important aspect of performance, and is difficult to put numbers on.

Arpex had clear performance targets. I wanted to achieve a decent upwind angle, and sail at about 80% of wind-speed, so that I would sail at 6-8 knots, in our 7-9 average wind conditions on the bay and around. Another objective was  ease of handling, with single hand command given at all times, while giving undisturbed comfort for a passenger. Undisturbed from maneuvers and weather - while still integrated with the helm person. At the same time, it should be a well mannered boat, with safe handling.

As described in other Performance Review articles, the speed and upwind sailing objectives were met. Just as the ease of handling targets.

Sail controls to Arpex come together at the helm position. The mainsail sheet sits right next to the helmperson, on a camcleat. It can be let go in a split second. Even from inside the cabin, it can be easily reached, at an arms length. At the same time, the sheet has a convenient reduction, so that no excessive force is necessary to bring the sheet in, in stronger winds. The jib sheets is right on the middle beam, and one can comfortably control it from the helm position, by holding it in hand, or by standing up, on the stable wooden deck.

Another safety factor, is that Arpex self steers without any problems. So, I can leave the helm, and do whatever I need to do. The boat won't breach, nor have any other abrupt attitude. At the same time, Arpex is fun to steer, and very reactive to the wheel.

The boat is also unsinkable, which helps to instill confidence. The ama has several watertight compartments, and the main hull has bulwarks, which divide the internal volume. Not having through hull fittings, also eliminates the risks of leaks.

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.

Arpex Review - Sailing Performance

The objectives regarding sailing performance for Arpex, were to obtain speeds under sail, in a range of 80-120 percent of the true wind speed. Considering an average sailing condition of 8-10 knots, this translates into 6,4 to 9,6 knots of speed.

I would consider this achieved. Such a range of speed corresponds to my perception of average speed. Arpex will als chieve speed of over ten knots. I have achieved 11,9 knots, which I saw on the GPS as a 3 minute average speed. And my impression is that we have also sailed faster than that. Maybe 12,5 to 13 knots. But the condition was not stressed. I suppose that a potential 15 could be achieved. To achieve that, Arpex would need a consistent 15-20 knots of wind.

From 18-20 knots, that it is where I start to think about reefing the main.

But in general, I feel Arpex lacks a little bit of sail area. I suppose the mast could be about 50cm taller. As a matter of fact, I could gain 100cm, if I stepped the mast on the deck. This could increase my sail area by about 4-6 square meters, between 13-20 percent. This would give higher speed.

But for now, I am thinking about options to increase sail area, without having to invest into major structural changes. The easiest way would be to produce a bigger fore sail. A large genoa, which would come from the bow. It would also increase about 4-6 square meters.

But the architecture for the foresail has not yet been defined. My first thoughts went into a asymmetric nylon sail. However, I feel that Arpex actually seldomly sails at large angles, which would profit from a light nylon sail, for beam reaches. Maybe a more genoa stlye would be the better solution for this boat.

Arpex Review 2 - Project Objectives

The chapter of my new series, which has the intention of making an honest review of Arpex’es performance until now, starts with a review of the very objectives of the project. Only looking at those first can we evaluate how the project performes.

Any person who is considering to own a boat, carries with him an extensive list of requirements. The better these requirements are clearly formulated in the beginning, the more likely it is that the boat owner and keeper will be a happy man, or woman.

My list was organized in the categories Sailing Performance, Livability and Creature Comforts, Maintenance Effort and Cost, and other General. Luckily, this list did not change throughout the project. I believe this is an important factor for the overall success of a project, and a cohere end product.

In terms of sailing, the requirements were guided by my overall objective of having a fun platform for experimentation, and relaxed sailing. I never looked at sailing performance in perspective of participating in regattas or any competition. As I am not keen on internal combustion engines, I wanted a boat on which I could maximize sailing in our moderate local conditions, taking advantage of a capacious deck, to enjoy the benign weather, and lovely views of Rio de Janeiro. The idea is to daysail in the Bay of Rio and around it, with overnighting capabilities for a couple, in comfortable and dry camping conditions. In the list of ambitions was also the capability to do the 60 mile crossing to Ilha Grande and back, under sail or engine, to spend a long weekend there.

In terms of creature comforts and cabin shelter, the idea has always been to keep things simple and light. But nevertheless comfortable and a good place to spend time. The simplicity also included the decision not to install any toilet or hydraulic arrangements and through-hull fittings. For urgent needs a bucket has been doing the job quite efficiently. A newly purchased propane camping cooker will provide ability for a hot drink or meal. I plan to purchase those solar bags, which can make it possible to have a hot shower at the end of the day. In general the big windows, which provide ample visibility have proven to be a success.

In general maintenance has been reasonable, in terms of effort and cost. I think Arpex has resisted quite well to the inclement exposure to sun, wind, salt, and general abuse.

In the next few posts I will look into those categories more deeply, preferrably illustrating with images and video.