GP14 Sailing Forums Forum Building mark 1 – in New Zealand timber type

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    • #23341

      Hello everyone,

      I’m new to the org and to the forum – and I don’t currently own a GP. I did many years ago (no.4561) and my plan is to be an owner of one again as I plan to build a mark 1 here in New Zealand for cruising with a family.

      M’y question for thé forum is around timber types and availability. The plans ask for Obechi for the beams, knees, king planks and carlins. It is not readily available here – but I could get my hands on Douglas Fur. Can anyone tell me if this is similar to Obechi in weight and softness? Or suggest another timber type? I already have the mahogany and the ply shouldn’t be a problem.



    • #23345
      Oliver Shaw

      There is a very long history of successful boat building (including yacht building) making the best use of whatever timbers are available locally;   and it is entirely reasonable to try to identify which of the timbers available local to yourself are most suitable for the job,  irrespective of what the plans say.

      Although I would not normally recommend sending retail quantities of timber half way across the world,  it might be worth your while to have a look at the Robbins Timber website,  if only for an analysis of the characteristics of a wide range of different timbers;   Robbins Timber

      Another useful website if you are considering Douglas Fir might be Collars,  again for information on the characteristics of the timber,  rather than expecting to buy from them at that geographical distance.   They are leading mast and oar manufacturers,  and they use either Douglas Fir or Sitka Spruce,  the choice depending on the particular type of mast,  because the two woods have different characteristics;

      Also some information here on obeche; .

      Also worth having a look at The Wood Database;

      In regard to rot resistance  –  always obviously relevant for boat building  –  I note from the last of these that Douglas fir is rated as moderately durable,  whereas obeche is rated as poor;   so it is a little surprising that the plans specify obeche!

      My recollection of the early GP14s which I have owned in the past is that longitudinal framing (stringers,  chine pieces,  carlins,  etc.,  were all in a light-coloured wood which I tacitly assumed to be pine.   I cannot be sure about the kingplank and the carlins.    However I am absolutely sure that the knees were mahogany.

      Hope this is of some help,





    • #23346

      Hi Jon,

      Welcome to the forum.

      Adding to what Oliver has suggested and being a retired joiner I would say that Douglas Fir would be a good choice but if you can then Cedar would be better as it’s lighter and much easier to work with.  Douglas Fir although durable can have very adverse grain when cleaning up. Best selected carefully for straight grain.  Check out my Self Build on the Association website in the News section. It’s a Mk2 build in ply recently finish and awaiting rigging. My King planks, Carlins, Stringers, Chines, Stem head and Hog were all in Cedar. You say your looking at a Mk 1 build, is this in preference to a Mk 2 build with its extra buoyancy? Hope this helps.


      • #23347
        Oliver Shaw

        And to add to Windy’s query about Series 1 as against Series 2,   dare I suggest that the choice is not entirely one-sided,  and particularly so for cruising.

        Both are great boats,  of course;   that almost goes without saying,  and especially on this forum!

        One of the design intentions of the Series 2 was that it should be quicker and easier and cheaper to build than the Series 1;   having never built either of them I cannot make that comparison from first-hand experience,  but my understanding is that this is indeed the case.

        In terms of the finished boats,  the Series 2 has a number of benefits,  particularly for cruising.    It has massive buoyancy,  and in the unfortunate event of a capsize it is remarkable how rapidly it will then clear the hull of water once you right the boat and get her sailing;   if there is enough wind to have capsized you in the first place then you can expect to be able to sail her dry within about two minutes (and possibly less) of getting her righted again.   By contrast,  if you capsize a Series 1 boat you may well need to resort to a bucket to bring the water level down to a point where you can start to sail her dry;   my own experience of deliberately flooding a Series 1 with newly installed transom scuppers (in order to try them out) was fairly disastrous,  and my very rare subsequent capsizes were not much better;   and I have heard mixed view from others as to whether the transom scuppers actually work on a Series 1 boat.

        An unrelated added bonus for cruising is the commodious storage pockets along the sides of the boat.

        All that sounds a very strong hand in favour of the Series 2.   But  …   …

        First,  in the event of a capsize the Series 2 is very prone to inversion,  precisely because of the underfloor buoyancy.    Various developments have attempted to address this problem,  but whatever version is sailed I would strongly recommend carrying masthead buoyancy as standard;  the popular 9-litre masthead float will not provide enough buoyancy to prevent inversion   –  indeed it is not designed to do so  –  but it will buy time during which the competent skipper/helmsman can take the necessary steps to right the boat.   Inexperienced skippers may wish to opt for the 40-litre masthead float intended for training establishments.

        Second,  the underfloor buoyancy reduces the space between the thwart and the cockpit sole.   Personally I never found that a problem except for one situation;   if you wish to camp aboard  –  which I appreciate is firmly a minority situation  –  that reduced space makes it impossible to sleep aboard the boat underneath the thwart,  and it is necessary to rig some sort of sleeping platform above the seating instead.    By the same token,   in a Series 1 boat,  any small amount of water that comes in overnight,  via the transom flaps or otherwise,  remains below the floorboards,  so you can keep your kit dry;   in a Series 2 any such water flows along the cockpit sole to the self-bailer pockets,  and once those are filled any further ingress of water produces a wet floor,  so it can become more difficult to keep your kit dry.

        The above may possibly influence your decision whether to build Series 1 or Series 2.

        Finally,  a correction to the terminology;   the terms Mk1,  Mk2,  etc (up to Mk IVa) all refer to fibreglass boats;   the terminology for the different types of wooden boats is Series 1,  Series 2 (and,  I think unoficially,  Series 2a).




    • #23348

      Thank you Windy and Oliver,

      Your answers  are very helpful and have given me much to consider – I must admit that I hadn’t considered the series 2 as an option because I’d wrongly assumed it was designed for increased speed and performance rather than for the cruising/day sail enthusiast but also as I know the series 1 so well my inclination was toward that vessel.

      And with regard to the home/self build – if the series 1 is a more challenging build then so be it – I’m in it for the challenge and for the pleasure of building something in wood. I have a background which includes furniture making and fabricating timber sculptures so I’m reasonably confident that I can rise to the challenge.

      Thank you Windy for the timber advise – I had thought that Cedar would be a good option and it would appear that New Zealand has plenty of good stock – and I think it’ll be a more attractive option than the Obeche. And Oliver, like you I’d always thought my old GP had Pine stringers and Chines – but having looked at lots of images of Obeche its colour is very similar to that of Pine so maybe that was what it was. On another note – in my online search for an alternative I found many comments from modelers and craft based woodworkers who use Obeche because it’s easy to sculpt but worryingly referred to it as a harder version of Balsa – not sure about that!

      I have plenty of time to keep looking – I’m not in a rush and there are plenty of jobs on our wooden house to complete before I can start the build but it’s very exciting to look and plan and dream!

      Oh and would you have any comments on timber spars? Any experience here?

      Thanks again



    • #23349

      Hi Jon,

      Good luck with your plan/dream. Mine was realised at age 70 to give my 3 new born grandchildren some memories, just need to get it rigged now.  No experience regard timber spars I’m afraid but Olivers link to Collars recommend the timber species and I’m sure there are websites out there to help with construction. All the best and when you do start your build please keep this forum informed.

      Regards  Windychippy

    • #23350

      Obeche is used for the stringers and structural framework of many boats because its very light and flexible. These don’t need to be especially strong so it was desirable to go all-out for minimum weight to centralise as much of the weight as possible rather than have heavy extremities, particularly the stem and transom – you see quite a few S1 GPs with obeche transoms with mahogany inserts where the fittings go.

      If the boat isn’t going to be raced in its class this level of detail is probably unnecessary and you would undoubtedly get away with using a heavier timber such as ash which maintains the flexibility but is stronger and far less prone to rot. Cedar would also work from the strength/weight point of view but is it flexible enough to go round the curve from the shrouds forward without steaming? (It may be, I don’t know. I know its widely used in rudders and centreboards and also the hog/keel in some classes)

      I wouldn’t get too hung up over weight from your perspective and I think if you aim for minimum weight with no correctors you’ll be ok. The difference between a metre 1×1 inch of obeche vs ash or mahogany is very little and whilst it all adds up you have six kilos to play with!

      I would recommend something harder such as ash or sycamore for the carlins as these will take a beating and cedar/obece dent easily.

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