The initial mk1 design

It is worth restating a few items about the initial design, which we now generally term the mk1 series of the Corbin 39. There were some key design selection decisions that clients had to make regarding their mk1 purchase, quite irrespective of internal personal fit-out preferences:

• twin-masted ketch or single-masted cutter-rigged sloop;
• centre cockpit without pilothouse, or aft cockpit with pilothouse;
• tall double-spreader mast, or shorter single-spreader ‘cruising’ cutter.

Together these created quite a variety of individual boats, and this in turn leads to a certain amount of unavoidable complexity when describing and recognising the changes in the mk2. Good example are the #73, Jakatar which is a unadorned mk1 cutter, or #69, Joint Effort which is also a mk1 cutter but has the short bowsprit for anchor-handling, but with the forestay in the original position on the bow, or the mk1 centre cockpit ketch #66, Pinguescence which has received the full bowsprit & forestay change described below.

The 1982 fire

The late 1982 factory fire destroyed many of the moulds. It is unclear whether the hull mould was undamaged, or whether they built a new mould from an existing hull or the initial ‘plug’, but the outcome was that the hulls remained unchanged throughout the entire production run, together with the integral keel, the skeg, and the rudder.

However after the fire they took the opportunity to make some design revisions to improve on various aspects of the mk1. These revisions were all in the superstructure moulds, and the fitting out, so in all cases the hull remained unchanged. It also appears that the majority of the deck mould remained unchanged, although some minor adjustments were made to where the various through-deck penetrations for the superstructure and where the cockpit tubs were cut, and most prominently to the shaping and location of the aft-cockpit side-coamings. We are unsure if they achieved these changes through a modular mould structure, or in some other manner. One report says that only the rear half of the deck mould was redesigned, and this would fit the evidence.

The fire itself was in late 1982 at the second yard. We are not exactly sure when the fire was, but we know from the records that it destroyed the six hulls numbered #059, #112, #117, #120, #122, and #128. Since surviving hull #127 was stamped as being moulded in 08-1982, and since surviving hull #129 was stamped as being moulded in 11-1982 it seems likely that the fire occurred in perhaps September of 1982 with the new factory in operation by November 1982 at the third yard.

This is relevant because it means that every Corbin 39 that is from #129 onwards is definitely a mk2, or at least we have yet to come across one that is not. However some of the earlier hulls had not been fitted out by late 1982, and so some of the owners took advantage of the design changes to buy the new superstructure moulds, and to incorporate the fitting-out changes. This means some pre-1982-fire hulls are also mk2 boats. That is why it pays to observe the detail of the changes and compare them with each individual boat. A good example of a mk2 using a hull that predates the 1982 factory fire is #123, “Bockra” which can be very easily compared side-by-side with two post-fire examples of the mk2, the #129, “StradiMarius II” or the #155, “Blue Run” (ex “Reverence”).

The mk2 changes, the “Edition Special”

The changes primarily addressed sailability and habitability. They were revealed with #129, “StradiMarius II” which was Marius Corbin’s own boat, and they were branded as the “Edition Special” or “Special Edition”.

Sailability

Clearly weather helm had been an issue for some of the mk1’s. Anecdotal evidence is accumulating to suggest that weather helm was most noticeable in the mk1 tall-rig cutter, less noticeable in the mk1 short-rig cutter, and not an issue in the mk1 ketch. Although it could be easily addressed it was nevertheless not ideal or perfect. Update : read the FAQ entry on weather helm which has many links to a comprehensive study on the subject. See https://corbin39.org/faq/?Display_FAQ=1256 . Bottom Line : it turns out that whilst mk1 weather helm did exist, it did get solved, and in any case was never that big an issue.

Anyway at the time ordinarily the four coping strategies that had been taken by mk1 owners were to :

• reef the main somewhat early;
• cut approximately 3′ off the foot of the main boom and make a correspondingly slim mainsail;
• make underwater hull changes to increase the skeg area;
• install a bowsprit braced with a bobstay to move the forestay and foresails forwards by approximately 3-feet.
• There were some other experiments but those describe the main pathways.

In the event Marius Corbin elected to add the 3-foot bowsprit to all of the mk2’s and thereby move the centre of the effort of the sailplan forwards. This was assisted by the mk1 design option that made provision for both a double-masted ketch rig and a single-masted cutter-rigged sloop. If you look at the deck and internal hull structure layout on all the mk1’s  and indeed all the mk2’s you will observe that there are two locations that the mainmast could be sited which are spaced 81cm (32″) apart. Initially, in the mk1, the design intent was for the mainmast of the ketch to go in the more forward position, whereas in the cutter-rigged sloop the original design intent was for the mainmast to go in the more aft position. Viewed externally the more forward position lines up just forwards of the three main-saloon hull portlights, and (in the aft-cockpit pilothouse layout) is just in front of the fwd pair of the four main saloon deck windows/hatches. Viewed internally the more forwards position of the mast is easily identifiable by the closeness of the compression post to the normal position of the main transverse bulkhead of the saloon (be really careful when looking at mk2 interior layout sketches of this from Corbin, as in some sketches they obviously re-used some of the old mk1 sketches without altering this detail). In contrast internally the mk1 compression post plunges straight through the centre of the normal position of the saloon table. So the changes to the location of the sailplan to move it forwards can be summarised as being the addition of a 3-foot bowsprit and a moving forwards of the mainmast of the cutter by 81cm (32″). This was entirely successful and in the mk2’s, even those with the taller double-spreader mast, the weather helm is nothing unusual or untoward and indeed the boat can be managed so as to create lee-helm if one were to desire !

So the main recognition features of these mk2 sailability improvements are the forward stepped mast (81cm = 32″) and a forestay running to a 3-foot long bowsprit that is fully braced with a bobstay to the stem near the waterline. A section further down this page gives side-by-side photos of these features.

Another rig-related point to note is that all the mk2 sloop/cutter-rigged boats are fitted with a taller double-spreader mast and that this has a split backstay as the factory-standard, with two external stern chainplates. In contrast almost all the mk1 sloop/cutter-rigged boats have only the single central backstay, with one internal stern chainplate. This is so irrespective of whether the mk1 was a tall mast (double spreader) or a short mast (single spreader) version. However there are a few mk1 sloop/cutter-rigged boats where the owners elected to fit a split backstay so this cannot be taken as firm evidence of a boat being a mk1 or a mk2. Of course the other exception to this was the ketch rig in both the mk1 and mk2, where the main backstay was split to go either side of the mizzen mast, but chainplates were still bolted to internal knees.

Habitability

The most obvious changes were to : increase the width of the aft-cockpit ‘tub’ so as to make the cockpit slightly more commodious, and to increase the height of the pilothouse roof, and to offer a pilothouse option for the centre-cockpit layout (which previously had not had this option).

The aft-cockpit was deliberately made fairly narrow in the mk1 so as to increase snugness at sea. Inspection of the sides of the mk1 cockpit show wasted space in the bulwarks and coaming, and in the mk2 these were pushed outboard so as to create a cockpit that is significantly more ample. Whilst the mk2 cockpit is by no means a modern sun-lounge, it is definitely more generous compared to the mk1. This is not so noticeable in photographs, or even in person, unless you have experience of both the mk1 and the mk2 to make the mental comparison, so it does not serve well as a visual recognition feature unless you have the side-by-side pictures below to guide you.

The pilothouse roof was made slightly higher as it was realised that it was so low a profile in the mk1 that it did not obstruct forwards vision from the cockpit, whereas it was also realised that a small increase in height would greatly improve visibility from inside, and light penetration to the interior, and headroom. The mk2 pilothouse is reportedly about 6″ higher than the mk1 (DS note : I have yet to run backwards and forwards between a mk1 and mk2 with a tape measure to be absolutely sure about this measurement). The most obvious recognition feature is that there are three smaller forwards-facing windows in the aft-cockpit mk1 pilothouse, whereas there are four enormous forwards-facing windows in the aft cockpit mk2 pilothouse. Once you have compared photos of this aspect of the aft cockpit mk1 and the mk2, as shown below, you will see this notable visual difference and it serves as a good recognition feature, but you do need to watch out for the centre-cockpit mk2 which seems to have three windows ! So far there have been no reports of a boat with a mk2 pilothouse but a mk1 cockpit so it rather seems as if this was a matched pair of mouldings.

The mk2 pilothouse was initially available as a bolted-on structure, just like the mk1 pilothouse. After the first few of these were built the mk2 pilothouse was then completed as an integrated glassed-in structure. This eliminated a leak-path between the deck and the pilothouse for water. Subsequently some of the first mk2 boats have glassed-in this joint, as have some of the mk1 boats.

In the mk1 the centre cockpit version does not have the possibility of a pilothouse. The mk1 centre cockpit is open with a wind deflector of canvas or custom-made light fibreglass up front, looking forwards towards the main mast. An example of this is #086, “Jack Iron” if you want to look at photos. In the mk2 centre cockpit the design changes allowed for the installation of the same pilothouse as the at-cockpit mk2, but in a more forwards position, close up to the mainmast. There do not seem to have been many of these made, if only because the aft-cockpit pretty much was the client preference, but nevertheless a good example of this is #176, “Marion Mae” which was also the only fully factory-fitted out ketch to have a red hull.

So what about in-between boats ?

As you look around the world of Corbins you will realise that some folk have incorporated elements of the mk2 when carrying out refits to what were initially built as full mk1’s. These are many and varied. The most common change is to add a bowsprit and move the forestay forwards, thereby alleviating (or at least reducing) the onset of weather helm. Since many of the mk1’s incorporated a bowsprit at the very beginning, for anchor handling and bottom-observation purposes, this is often quite easy to do. The main note of caution would be that a bobstay brace needs to be fitted, and it all needs to be sufficiently structurally strong to carry the rig-loads.  In principle these refits could shunt the mast forwards, but that is seldom done as it would be a lot of extra expense and effort for not much extra gain. As well as this there are also all sorts of pilothouse and deck-saloon modifications out there which bear testament to the general adaptability of the Corbin 39 underlying design.

Recognition photos

Cockpit: The aft-cockpit is considerably more spacious in the mk2. See how narrow the footwell is inthe mk1  #050, Opportunity on the left vs the mk2 #189, Kalliste on the right.

Aft cockpit pilothouse windows: The aft cockpit pilothouse is higher in the mk2 than the mk1 and this is most obvious in the forwards-facing windows. The mk1 (#016, Honah-Lee) on the left has the three shallower windows typical of the mk1, whereas the mk2 on the right (#186, Visitant) has the four deeper windows typical of the mk2. The height difference in the coachroof of the pilothouse is not so obvious in photos, but more obvious when inside.

Mainmast base location on deck : the aft position was used in the mk1 sloop/cutters such as #119, Tammie Norrie, whereas the forward position that was initially intended only for the mainmast of the ketch was used in all the mk2 such as 154, Brillo del Sol. The neatly painted deck of #073, Jakatar shows a mk1 with the aft mast position occupied and the 81cm (32″) between this and the obvious alternative forwards mast position.

Mainmast compression post: In the mk1 sloop/cutter the aft-position of the mainmast means that the compression post generally is set fairly prominently in the centre of the saloon table as in these photos from #073, Jakatar. In contrast in a mk2 the compression post will ordinarily be at the forwards end of the saloon table as shown in this picture from #123, Bockra.

Centre cockpit pilothouse variant: The mk1 centre-cockpit does not have any opportunity to fit a pilothouse, so the centre cockpit is just a bare tub (such as #86, Jack Iron on the left) to which many owners install fabric or fibreglass windshelds of some form (such as #111, Merida). In contrast the mk2 was able to use the same (or similar) pilothouse moulding as in the aft cockpit version and install it into the centre-cockpit, but running right forwards to by the mainmast, as in the examples of #130, John Galt and #167, Marion Mae. There are a couple of points of detail to watch for. Firstly the centre cockpit mk2 pilothouse was available both as a ketch (CC-PH-K) and as a cutter/sloop (CC-PH-C). A couple of good CC-PH-K examples are #130, John Galt and #167, Marion Mae, whilst #140, Urantia is a good CC-PH-C example. A second point is that the mk2 centre-cockpit pilothouse seems to only have three forwards-facing windows and so can be easily mistaken at first glance for a mk1. However they appear to be the deeper windows of the mk2 pilothouse rather than the shallower windows of the mk1. We are unsure, but it is possible that they used the mk2 windows but omitted one of the central panes and made a reduced width pilothouse so as to achieve some side-deck, perhaps by reworking the mk1 pilothouse mould in some fashion. Until we get a really detailed look at a mk2 CC-PH-x with a co-operative owner we are unsure exactly how this was done. A related point of detail is that so far we have not identified a mk2 centre-cockpit that does not have the pilothouse.

The bowsprit: This is a recognition feature that must be handled with care. On the far left is a original mk1 bow (#116, Bright Eyes) with no bowsprit and the aft-placed mainmast. In contrast on the far right is an original mk2 bow (#131, Two Crows) with the final design evolution showing the 3-foot long bowsprit and the bracing bobstay that accommodates two anchors, and this has the forward-placed mainmast. In between are two examples of a mk1 that have been fitted with bowsprits and bobstays, but which retain their initial fit of the aft-placed mainmast (#113, Sunrise and #071, Santy Anna). Our understanding is that this retrofit to the mk1 of the bowsprit cures most, if not all, of the weather helm issue which is why it was so widely adopted as being a relatively straightforwards solution with no need to intervene regarding the mast or chainstay locations, as well as giving a good anchor platform. On some of the mk1 boats you will see a short bowsprit that was intended for anchor handling but which does not take the forestay. Note that the full 3-foot long bowsprit must be braced by a bobstay to withstand the forestay loads in the mk2 version.

[2019: this ‘quickie’ discussion of these issues added to the 2015 FAQ as a starter. Updated 2023. DS]