Considerations when we choose our new Mei Poh (Catalina 387):
Choosing a boat is an investment that requires a tremendous amount of thoughts and homework, to avoid ending up with a wrong boat, high expenses and selling at a loss, as was my experience with the Neptune.  We decided for a new boat, as the second market in the region does not leave you with a good choice if you know what you are looking for and are not willing to compromise. 

The following starting points were considered:

1. We are cruisers and not racers and comfort (motion and accommodation) is more important than speed.
2. The new boat must be small enough to handle single handedly (we sail as a couple, meaning that on longer trips, you will be just alone on watch for many hours) but big enough to give us the space we think we need for our plans (long coastal sailing in the Australasian region)
3. Stability and seaworthiness is of prime importance
4. Comfortable move also through rough waters
5. Reasonable speed potential in the relatively calm waters here in the regions around the equator
6. Construction material: fiber, steel, aluminum
7. Lay out of interior, especially the galley
8. Esthetics and budget
9. Easy maintenance (boat and boat hardware)

Boat size.
Most boats that circumnavigate (many times a couple alone, sometimes with (small) children) are in the 40 to 50 foot range. Reason for that size is not only safety and comfort, but also required space to store all needed equipment and supplies. As we are not planning to circumnavigate but do coastal sailing only, our trips between stops where we can stock up will be shorter. A 40-footer might then be preferable over a 50-footer as it will be easier to sail single-handed. And of course there is also a matter of budget, not only for the purchase but also for the maintenance, which increases exponentially with boat length! I short-listed a number of production boats around 40 foot.

Seaworthiness and stability.
Obviously a boat for long coastal sailing should have a CE category A qualification. (meaning that according to EC guidelines it can withstand significant seas of up to 4 meter and force 8 winds for prolonged periods of time). Most if not all boats over 30 foot will have that qualification. Factors that are important for this CE qualification are displacement, beam, ballast ratio, angle of vanishing stability to name a few, and the individual data are in most cases not readily available from the boat builder’s prospects. But, other, simpler indicators for stability and performance can, however, be calculated from characteristics provided by the builder.
The length to beam ratio is an indication of stability (‘form’ stability). A normal value of a boat in the 40-foot range is 3 to 3.5. A very beamy boat (a low value) might not sail well, especially when close to the wind, and might have the tendency to broach in gusty winds. At the other end, a less beamy boat will generally be faster.
The ballast ratio (ballast weight/total weight) is indicative for ‘weight’ stability. Lower values are around 30 % and some (long keel) boats have a ratio of around 50%.  Boats with a small ballast ratio heel relatively easy, thus ask for early reefing and they might on longer hauls not be very comfortable. Based on boat characteristics as beam and displacement a capsize factor can be calculated. The lower this factor, the lower the risk that a boat will capsize due to excess wind or waves. Most boats in the CE A category have a capsize factor of  2 or lower. The angle of vanishing stability (AVS) of the Catalina 387 with wing keel is about 130 degrees, a relative high value considering that sea going sailing boats should have  an AVS of at least 120 degrees.

Motion comfort.
Based on displacement, waterline length, hull length and beam a ‘motion comfort’ factor can be calculated. A relatively light boat will have a lower comfort factor, meaning that in choppy seas the movements will be quite lively, whereas a boat with a higher comfort factor will move more steadily, giving the crew a more comfortable ride (sail). Obviously for long(er) distance sailing this is preferable as it is less tiring.
The ratio of hull length to waterline length is also indicative for a more comfortable sail. A boat with greater ‘overhangs’ is less prone to pitching.

Speed.
The (theoretical) hull speed of a displacement boat can be calculated from waterline length (lwl, feet): speed (knots) = 1.34*sqrt(lwl). The displacement to length (lwl) ratio is indicative for the acceleration capacities of the boat under sail. A light boat will accelerate fast, which might lead to uncomfortable motion in a seaway.

Sail area.
Sail are a is an important factor in the speed potential under sail, but the displacement has to be taken into account. A heavier boat needs more sail area (SA) to be move than a light displacement boat. For this the SA/displacement ratio is calculated from the sail area (100% fore triangle) and the displacement. Speed under sail can be calculated from waterline length, displacement and sail area (velocity ratio) and is normally expressed as ratio to hull speed. Most sailing boats have a velocity ratio that is slightly over 1.

Construction material.
For smaller boats (35 to 40 foot) a steel boat with a reasonable hull thickness automatically becomes a heavy boat. For this reason steel as material for a new boat was out of the question as it would be too heavy for a 40 footer. Aluminum is a good alternative, but aluminum boats are prone to corrosion and for example loosing a copper washer or coin in the bilge can result in serious corrosion to the extent of a hole in the hull. Steel and aluminum boats are generally not production boats (there are exceptions) and hence relatively expensive. Relatively low cost boast from Taiwan or China were not considered. Also, steel and to a lesser extent aluminum asks for regular painting, and thus higher maintenance cost. So the final choice would be a fiberglass production boat. 

Lay out.
The lay out or interior design of a boat is not only a matter of taste. Those people who have sailed in relatively heavy weather other than for a short regatta know how difficult it is to feel comfortable inside a moving boat (in terms of space, ventilation, sleeping comfort).  But even on shorter trips where sleeping comfort is not an issue, the use of the galley is. There is always a need for a warm drink or some snacks and the galley must provide those possibilities also in heavy seas and under heel. For that the person working in the galley should be enclosed. A galley parallel with the length axis of the boat is not comfortable to work in in heavy seas, especially not when the boat heels. Also, ideally the galley is close to the companionway, not only because of ventilation and easy removal of cooking smells, but also to serve or get food to the cockpit.
Sleeping in a pitching, rolling and/or heeling boat is never comfortable if at all possible. But one thing we learned from the Jeanneau SO (were we slept in the fore peak) is that in a pitching and rolling boat the forepeak is an impossible place to be. You are constantly catapulted due to the very high acceleration forces in the forepeak and the noise of the hull when pitching can only let a dead man sleep.
Otherwise, the new boat only needs to accommodate two of us, so space wise there should not be a problem in the 40 foot range. Locker space should be as much as possible and if not existing, then at least possible to make without structural changes.

Budget.
Although budget is always an important factor (not only if you can, but also if you are willing to pay an x amount for a boat), we decided to leave this open for the beginning. However, along the way after inquiring, we had to tell a sales person that the budget was (unfortunately) not sufficient.

We selected the following boats (a mixture of cruiser/racers and cruisers), some quite often used by blue water cruisers: Bavaria 37, Bavaria 39, Beneteau Oceanis 393 (changed to Oceanis 40 in 2007, basically the same hull and characteristics), Catalina 387, Catalina 40, Dufour 425, Elan 384, Etap 37, Halberg Rassy 40, Jeanneau SO 39i, Najad 38.

We calculated, based on the data available from prospects or website a number of performance parameters. Theoretical hull speed as well as velocity ratio was, as expected, very similar for the boats, with slightly higher values for the 40 plus footers. Of the heaviest boats (Catalina, HR40 and Najad 38) only Najad compensated this with a relatively high sail area, so the Catalinas and HR40 had the lowest SAD ratio. Based on the comparative data the Oceanis, the Bavarias, the Etap, the Elan, the SO 39i and the Dufour will be more lively boats than the two Catalinas, the HR and to a lesser extent the Najad. However, the motion comfort factor and the capsize screening factor of these boats were much better.
Some of the pre-selected boats use sail drives for their propelling (Bavaria, Etap, Elan). Although sail drives undoubtedly have advantages over propeller shaft driven boats, the fact that our new boat will be constantly in salt water (corrosion risk of the aluminum sail drive), the possibilities of hauling out in the region are limited (in case of a leaking oil seal of a sail drive), limited service possibilities and a higher risk of serious water leaks compared to propeller shaft let me decide to not go for a sail drive. Bavaria used to give sail drive or propeller shaft as a choice, but does not do that anymore.
We had a look at the Etap 37 (perhaps nostalgia??) but in addition to the sail drive issue, the internal space was also limited, to be expected due to the unsinkability of that boat (closed cell polyurethane foam between a double hull).
As we do not want to race but to cruise in comfort, the choice was down to the two Catalinas, the HR 40 and the Najad. Unfortunately my budget did not allow choosing for HR or Najad. While checking out the two Catalinas, we did not like the two steering wheels in the Catalina 40. The final choice was made for the Catalina 387.

Other factors that played a role in the decision:

• The overhangs of the Catalina 387 are relatively high, leading to a more relax seaway

• The ballast ratio is relatively high suggesting a stiff boat. In addition to the relatively low SAD ratio it might mean reefing at higher winds compared to other boats.

• The moment of inertia (an empirical term indicated the resistance to rolling) was much higher for the Catalina than other boats, with exception of the HR 40.

• The Catalina has no wood outside (even handrails are stainless steel), we liked the boat, specially the very roomy interior and boat gives overall a very solid impression.

The following table gives some of the characteristics and stability factors calculated for the finally listed boats. The last column shows the values for our ‘old’ boat, the Jeanneau Sun Odyssey 33. Based on the values we can not only expect a faster boat (hull speed) but also a more lively boat (SA /Displacement and a much more comfortable boat (motion comfort)

Comparison of basic characteristics and performance, stability and motion comfort between some selected boats and our previous Sun Odyssey 33.

the 'desirable' values are for a coastal cruiser. For a (club) racer other values apply