--Originally Posted 5/12/13--
In a Dutch shipyard on 8/15/38, the soon-to-be Polish submarine Sep, at left, swathed in scaffolding, is well along in construction, next to the just-begun Dutch O23 (center) and -24 (right).
As longtime ModelFleet visitors will know, I have lamented the utter desert of models of Dutch WWII naval subjects - most pointedly the subs, of which I still have seen not a one. Thus, it was with great excitement that I learned both that some Polish WWII subs were actually designed and built by the Dutch - and that model manufacturer Accura (or someone even more ancient - kit looks like an early Heller) released one of these, in styrene (who cares how crude or antiquated!), in 200-scale:

Click on Image to EnlargeFor which I have Gus Hager to thank - THANK YOU, Gus! - for the Accura Sep, at left. Sep and her sister Orzel, the two (identical, AFAIK) Polish subs designed and built by the Dutch, were reputedly closest to - essentially variants of - the Dutch O19 class - the class immediately preceding the new construction seen in the 1938 pic, above.
However, Sep/Orzel did not bear as close a resemblance - at least, not on the outside, as depicted by my Accura model - to the late-'30s Dutch O-boats as much as to another, significantly earlier, vintage of Dutch boats: the K11- and K14 classes, shown at right. At top, the Accura mold, its two main pieces (halves) taped together, is compared from roughly the same angle as views of K12 (middle) and K17 (bottom). Disregarding the difference in the sails - superficial items, apparently of unique design on the Polish subs and in any case varying widely (over time) on the Dutch subs, as well - the biggest (visual) difference is seen in the top casings. Both classes of K-boats have a conformal, highly dished-in casing, forming a sheath over the pressure hull for the entire length of the deck, and extending clear down/out to the waterline. At the bow, the Accura mold exhibits features somewhat intermediate between K12's level, raised step and K17's strongly upward-curving sheer, reversing to a pronounced round-down, at the prow. Admittedly, seen from these angles and only above the waterline, the K-boats don't particularly seem to resemble the Accura model - though they are already notably closer than the subsequent O-boats (see below).
But it's
aft that the "family resemblance" really becomes apparent:


Click on Image to EnlargeAt left, the knife-like casing, aft - exposing more of the underlying pressure hull - reveals the essential resemblance between model and the real thing: K11 (upper-middle) and K12 (lower middle), the latter seen grounded off Sydney, Australia, shortly after the war.
Of course, it is the overall form of the hull - determining the fundamental resemblance (or lack thereof), as well as feasibility of bashing a model of one, into another - that is most clearly revealed by
drydock photos. And at center, accordingly we can immediately see the resemblance, at the stern, between the Sep model and K15 - absent some bulging torpedo tubes (note on the mold plastic, crudely indicated in tandem), substantial sheathing over the propeller shaft and significantly different location of the rudder, further forward on the model. It is easy to visualized addition of the above, plus the dished jacket of the casing atop the model, to instantly produce a strong if not total resemblance to this K14 class, aft. At right, exactly the same is demonstrated (left side) for the K11 class, by comparison against a pic of K11 herself (top-left), in drydock late- or post-war. Note the good view of the rudder, right aft, as fitted (to both classes).
On the right-side, a bows-on comparison against K14 (now seen in late 1943) again suggests a strong similarity in hullform overall - and even in the round-down at the bow. However the deck can be seen to present another major difference - second only to the top casings, above - as the K-boat decks (again, for both classes) widen continuously until clearing the sail, outboard, while on Sep/Orzel the deck remains relatively narrow, flaring out only at the island, to go around it before again pinching abruptly back narrow, to continue aft.
Clearly, the matchup at the bow is not as obvious as at the stern - however we can determine that it is certainly in the ballpark:
Click on Image to EnlargePhotographed in drydock December 1943 (top), K15 reveals her bow (including U-boat-type forward planes!), at first glance perhaps looking rather different from the Accura mold (bottom) - however careful examination reveals that it is mainly just the
profiles which differ, and that more fundamental similarities - especially regarding modelling/conversion - are actually in evidence. Observe the hull shape near the
waterlines (level with the top of the upper torpedo tube - and also conveniently molded onto the Accura hull), and then visualize the model with the new top casing installed: the appearance there will become a very strong, if not perfect, match. Admittedly the "chin" of the Accura mold is much more upswept, and would need to be considerably augmented - or actually, I would probably just cut open and pivot downward the existing chin/keel, and plate-in the resultant void(s), in the area around the torpedo tubes. Likewise, the top-forward round-off would have to be greatly enhanced - again, I would do this more by cutting and rotating hull pieces, as part of the above, than by straight, brute grinding-down. The takeaway being that the forward pressure hulls, despite their differing profiles, of both taper (horizontally, from the beam) in a very similar way: gradually, with no bulging and/or dishing, straight out to their bows.
This is definitely
not what we observe of the immediately pre-war classes of O-boats (reputedly closer-related to Sep and Orzel):

Click on Image to EnlargeAt left, as O19 slides down the ways 9/22/38 (top), she reveals not a smooth, knife-like bow as above, but one with pronounced bulges, overlying a significant dishing. The bulges accommodate mainly the torpedo tubes, but significantly also something else (very likely a down-looking sonar), extending down to the chin. These are all underlain by a dishing caused by a more abrupt tapering of the pressure hull proper, just aft of the tubes. Exactly the same is observable - only better - in pics, at right, showing the O21-class boats O22 (top) and O25 (bottom), in drydock 4/2/40 and launching on 5/1/40, respectively.
Astern, as suggested at left (bottom) by a pic of O20, underway circa 1939, the O-boats do seem to have retained much the same appearance - and presumably, resemblance to Sep/Orzel - as the preceding K-boats, above. But note that, amidships, the O-boat hulls do not quite become cylindrical, but remain slightly flattened at the beam and especially towards the top, where they meet the casing. Clearly, these hulls were further removed/evolved from the Polish subs than were the K11- and -14 boats, and - especially combined with the very wide, flat casing-sides of the O-boats - made for a very different appearance.
Just to cover one more possibility, I searched out the following pic of a significantly earlier, (1-boat) class of O-boat:
O16, a true contemporary of the K-boats shown earlier, appears to have O-boat hull- and casing features - in detail - exactly the same as seen on the later classes of O-boats, above.
From a modelling point of view, admittedly the O-class casings would be far easier to scratchbuild the than those for the K-boats - however this advantage would seem (more than) offset by the other, integral and extensive mods to the pressure hull - and bow, in particular - indicated above. Moreover, the Accura Sep/Orzel mold does not appear the best foundation for an O-boat, which seems very likely could more profitably be provided by some combination of TypeIX Uboat, possibly TypeVII Uboat and/or even Gato fleet boat hull components.
Either way, the above Dutch subs - both K- and O-classes - spawned some fairly historic boats, including some operating out of Fremantle, Australia (as I personally, am most interested in). More on that, to come...
Cheers,
-Matty