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Thread: Sea Harrier

  1. #1
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    Default Sea Harrier





    My last sailing canoe ‘Harrier’ (http://www.songofthepaddle.co.uk/for...hlight=Harrier) is a lovely boat which sails very well, but is not ideal for multi-day trips or for use on the sea. Predictably, I decided to build a new boat (the ninth in recent years) that would overcome these issues. It would need to have large deck hatches for easy storage of kit, space for on-board storage of a small trolley, and be sturdy enough to cope with bigger waves. I thought that it should be slightly longer than the JC10, on which the Harrier was based, with a slightly more rounded hull and a bit more freeboard. So, with some uncertainty, I entered the field of boat design. As it would be a modification of the Harrier for use on the sea, she would be called ‘Sea Harrier’ – but I was not expecting a vertical take-off!

    I looked at a few different software packages for boat design and settled on ‘Delftship’, which is a free download for the ‘simple’ version https://www.delftship.net/DELFTwp/ I didn’t find it too simple and it took a while to get the hang of the programme. There is a library of hull designs developed by others and this included a laser dinghy hull which was a useful comparison. My approach was to input the offsets from the JC10 plans and then modify them as required. This screenshot shows various views of the hull having increased the length, rocker and freeboard, and rounded the hull. Codename JC20!




    There is a nice system for ‘fairing’ the modified contours and this screenshot shows the final shape with the deck added and some of the network of points visible. The software gives values and graphs for a range of parameters such as frictional resistance (skin friction) and ‘effective power’ and it is easy to delude oneself into thinking that you have created a speed record craft – but actually I didn’t fully understand what it all meant.



    Back in the real world, the offsets are printed out and I plotted them onto graph paper to produce a proper plan!



    Finally, in the workshop, ‘stations’ were cut from some Wickes hardwood ply……..



    ……. and mounted on a strongback.



    I enjoy exploring different construction methods so decided to build the hull using a foam core composite. For commercial builders this would normally be achieved by laying the foam inside a female mould, but for a one-off craft this is not a practical option so I would have to lay the foam over the outside of my male mould. To give adequate support I used various bits of leftover wood from previous projects to clad the mould.



    I covered this with a plastic sheet to stop anything sticking to the mould.



    I took advice on types of foam core and for a boat with fairly complex tight curves ended up with a material made by Gurit called Corecell Contour Scrim, which was 4.7mm thick and cut into about 10mm squares so that it would take up the shape of the boat. The fibreglass scrim holds it all together. I cut the foam into strips about 10” wide that could be fitted transversely over the hull – in hindsight these might have been better a little narrower.



    I held them together with superglue, supported temporarily by masking tape. There may be a better option as when it came to sanding down later, the superglue was harder than the foam so had a tendency to form ridges.





    When all the foam was on, the surface was coated with a slurry made of epoxy and ‘microlight’ to fill all the gaps between the 10mm squares and bond it all together.



    After sanding, the foam was covered with its outside layers of glass ….



    …… and carbon/Kevlar. There are some pieces of peel-ply used here to squeeze down the cloth.



    My initial plan was to leave the carbon/Kevlar surface exposed but I was not at all happy with the finish I managed to achieve. There were areas of discolouration and any attempt at sanding produced a Kevlar ‘fluff’. So in the end I used epoxy pigment and several fill layers to cover it. I like the colour but the process will have added unnecessary weight and little additional strength.



    The hull was then levered carefully off the mould ……



    …… put back on the building table and the mould put inside to allow the deck to be formed on top.



    The top edge was trimmed to align with the line of the gunwales.



    Enough of these artificial materials, it was now a return to wood. I like the appearance that can be created with strip-building so used a combination of western red cedar, Alaskan yellow cedar, and a little bit of sustainable Khaya mahogany.



    I used the non-staple method, requiring multiple spring clamps and many rolls of good masking tape (I find that the 3M 3434 has about the right amount of stickiness).





    The pattern was similar to the design I used on the original Harrier as I thought it looked quite sleek – western red cedar outside and yellow cedar inside.





    When all the strips were in place it was planed and sanded.



    For a bit of bling, I added a marquetry harrier to the rear deck. To inset the shape I cut the outline and made multiple 1mm deep holes as depth indicators before carefully chiselling out space for the 1mm thick veneers.



    Here it has been sanded and covered with a layer of glass fibre/epoxy.



    This is the coated deck before sanding again.



    And now the inside of the deck after adding a layer of carbon/Kevlar and planning the hatches.



    I used a method of hatch seal construction used for some sea kayaks, which is a bit time-consuming. It involves construction of a fibreglass flange that sits under the deck and the outer edge of the hatch, incorporating a recess which will accommodate a flexible seal. It is made directly on the inner surface of the deck, after covering it temporarily with clear release tape. Here the flange is upside down and the black spacer used for creating the recess has not yet been removed.



    After tidying up the flange and removing the spacer, it is bonded onto the deck with epoxy. It is very difficult to get a perfect hatch seal using this method as there is usually some flexibility. However, it does allow the deck pattern to continue over the hatches so the aesthetics are good.



    Lots of wooden backing pieces are then needed to allow various deck fittings to be screwed in place at a later stage. This means much time spent in trying to work out exactly where things should be.



    At this stage the bare hull weighed just over 20kg and the deck 8.5kg. Now they needed to be joined together so they were taped on the outside, the boat supported on its edge, and fibreglass tape put along the inside of the joint.



    I added a light spruce gunwale to reinforce the joint on the outside.



    The cockpit sides were fitted, incorporating the casing for the off-centre ‘centreboard’.



    There are two mast sockets, for sailing with or without the jib, and these were made using ABS pipe that had just the right inside diameter. I bought some HDPE rod and sheet via Ebay, and my brother kindly turned some mast fittings on his lathe, while I cut some other parts from the sheet. This shows the mast retention ring and parts for the swivel retainer.



    I made lots of toggles for the hatches.



    All fitted and the deck sanded, varnished and polished.





    Here you can see the rubber hatch seals which I made using two widths of door insulation. Experience so far suggests that the front hatch is fairly watertight but the back one leaks – some more fiddling needed. One problem is that the strip-built construction method leaves some tension in the wood, despite the glass/epoxy coatings on each side. When the hatch is cut out it distorts slightly making the fit uneven. This would be resolved if you had a flat deck and thick ply hatches, but you would have to compromise on the aesthetics.



    There are hatches for the side tanks, a bungee to hold the paddle, and a net to hold your drink container!



    I made some ‘winglets’ to allow hiking out when sailing. These were constructed using the same foam core method used for the hull, and were designed so that they could be easily removed if the wind dropped and paddling was required.



    A new outrigger beam was laminated – you can never have too many clamps……..



    The boat was then inverted and roof-rack supports and trolley constructed. To get the correct shape, the padding was taped to the boat, covered in plastic sheet, and the foam-core composite components constructed on top.





    This is the completed trolley that fits inside the boat, under the seat and rear deck.



    Name added and she is complete. She turned out a little heavier than I'd hoped at over 40kg and I think this was partly due to the problems I had getting an acceptable finish on the hull - in hindsight I would do this differently.



    First launch was on Windermere last Monday, with several chums from the Open Canoe Sailing Group – these photos kindly provided by Keith Morris.



    The mast and sail, winglets, outriggers, rudder and lots of bits of string have now been fitted!



    The wind varied quite a lot during the day, so I started with just the mainsail…..





    Later the jib was added.



    So far, so good. She sails well and the balance seems good, but there is plenty of scope for fiddling with things as I learn her foibles.

    I hope this description and my reflections will prove useful to anyone who embarks on something similar. I was not planning to build any more boats for a while but I've said that before and perhaps I could just tweak a few things on the next one ……………

  2. #2
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    Stunningly good sir!!
    Cheers,

    Alan


  3. #3
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    Awesome!
    You don't stop playing because you get old - you get old because you stop playing.

  4. #4
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    Wow

    Sent from my SM-T813 using Tapatalk

  5. #5
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    This is just too much. First Sam's marvel and now this. The skill, patience and bravery of taking it on are amazing. If I had put that amount of time and effort in, and produced such a splendid vessel, I would be too scared to use it. (I know you will use it though.)

    My current project is a very old glass and lots of tape slalom canoe, rescued en route to the tip, so when I dropped it today it didn't matter.

    As a yachty, I like the attention to detail. The vertical battens so that you can reef, a jib boom (but that does compromise a roller furler for the jib, which I think would be worth while to give a greater wind range of manageable sailing) the jamber on the main with semi central sheeting, Even with you small ish sail, I think you might find a ratchet block on the mainsheet, coupled with a lowered jam cleat, might make for easier response to gusts.

    But that all minor. Sea Harrier is fantastic.

    Impcanoe

  6. #6
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    Peter, you are a true artisan and I am in awe !!
    Nin Wanakiwidee Tchiman

  7. #7
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    Congratulations Peter, another stunning craft. 40kg isn’t too bad for a decked sailing canoe of that size. Better to be strong and robust rather than lightweight and fragile for a cruising sea boat

  8. #8
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    Awesome is a word bandied about by the youth of today often for something quite mediocre.

    This work of art that you built truely justifies the description "awesome".
    Big Al.

    Only when the last tree has died
    and the last river been poisoned
    and the last fish been caught
    will we realise we cannot eat money.
    ~Cree Indian Proverb

  9. #9
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    And another thing.

    I see you have persevered with the push me pull me tiller. Just feel that two half yokes and a tiller
    and an extension would be better, but then, although it would suit me because of 67 years of built in reaction to that system, your push me pull me has fewer moving parts, solves the transom horse / extension problem ( I know, its a sailing canoe, it doesn't have a transom) and it is what you are used to. so good on ya.

    I think I mentioned that at the time of my 10sqm International canoe ownership, there was rumoured to be, somewhere in the lakes, a 10sqm owner with the sames system as you. There was also someone with a square tube in the rudder head, through which passed a chunk of wood, curved along the vertical, which slid through on the tack and gave a different control movement.

  10. #10
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    WOW!!!!!

    That's amazing!!!!

    Sam

  11. #11
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    Quote Originally Posted by Impcanoe View Post


    I think I mentioned that at the time of my 10sqm International canoe ownership, there was rumoured to be, somewhere in the lakes, a 10sqm owner with the sames system as you. There was also someone with a square tube in the rudder head, through which passed a chunk of wood, curved along the vertical, which slid through on the tack and gave a different control movement.
    Is this along the same lines as thinging your thongs?
    - I don't understand a word of it!!

  12. #12
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    Absolutely beautiful.
    Paddler,blogger,camper,pyromaniac: Blog: Wilderness is a State of Mind

    Paddle Points - where to paddle

  13. #13
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    No Sam, no typo ( I think ).

    I feel really inconvenienced by this distance thing. As my kids used to say "are we going to need paper and pencil for this?" and in this case yes. In a nut shell or two. Most boats have a tiller on the rudder head, the circumferential movement of which moves the rudder and turns the boat. and the tiller normally lies along the centre line of the boat. Tiller steered sailing boats often have an extension on a swivel which enables the helms person to sit further away than the length of their arms. Sea Harrier, and I think Harrier, have the tiller at right angles to the centre line, with a very long extension (see the photos). this needs fore and aft movement to steer the boat.

    The other one has a longer tiller, also at right angles which slides and projects to next to the helmsman, and also needs fore and aft movement, but no extra extension.

    And I have enjoyed the thinging your thongs thread.!!!

  14. #14
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    Impressed
    trying to keep up!

  15. #15
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    Good explanation. No pencil and paper needed
    Sam

  16. #16
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    Peter

    Congratulations on another work of art. I love that you ventured into design too.

    Cheers

    Mark
    "I'd far rather be happy than right any day"..........Slartibartfast

    http://apachecanoes.com

  17. #17
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    Many thanks for all your kind remarks folks, greatly appreciated.

    Quote Originally Posted by Impcanoe View Post
    Even with you smallish sail, I think you might find a ratchet block on the mainsheet, coupled with a lowered jam cleat, might make for easier response to gusts.

    Impcanoe
    Thanks for your thoughts Peter. I have a ratchet block but moved it to the outer end of the boom as it was slightly too big for my mainsheet jammer. The commercially available mainsheet jammers are a bit big for a sailing canoe so mine is a modified swivel jammer - copied from Keith Morris's boat. It seemed to work very well on Monday and the release height was just right.


    Quote Originally Posted by DaveS View Post
    Congratulations Peter, another stunning craft. 40kg isn’t too bad for a decked sailing canoe of that size. Better to be strong and robust rather than lightweight and fragile for a cruising sea boat
    Many thanks Dave. I shouldn't have been too surprised by the 10+kg of extra weight over the Harrier as there is quite a lot more boat in terms of length and hull height. And this one does not flex over the waves, it is rock solid! I don't think weight is a major issue when on the trolley or in the water, its just maneuverability in the workshop or getting it on the car that becomes more difficult.

  18. #18
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    Absolutely fantastic. What a beautiful boat. Did I miss a step? When and how did you glass the inside of the hull?
    "Oh, Eeyore, you are wet!" said Piglet, feeling him.Eeyore shook himself, and asked somebody to explain to Piglet what happened when you had been inside a river for quite a long time.

  19. #19
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    You are right Tyro, I forgot to mention a step! The inside carbon/kevlar was applied before putting the form back inside and making the deck. I stripped off the cladding to make space then padded it up to the right level. The hull was then temporarily bonded to the form with some blobs of hot melt glue. Well spotted!

  20. #20
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    I should have known you would have it all sussed out. After all you must have had hours of time to think about it all whilst employed in some mindless task like sanding, etc.

    And for the man who has everything, a carbon fibre TROLLEY

  21. #21
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    Fabulous project...
    Quote Originally Posted by Impcanoe View Post
    ... a jib boom (but that does compromise a roller furler for the jib, which I think would be worth while to give a greater wind range of manageable sailing) .....
    But that all minor. Sea Harrier is fantastic.

    Impcanoe
    I've seen a clever system where a jib-boom is combined with roller furling

    The boom is tacked down to the centreline of the deck at about 25% of its length - the front of the boom carries the furler, the rear of the boom has an adjustable line for the clew and a fixer - line to a point just above the swivel the boom is sheeted in the same manner as is usually seen on a self-tacker.
    This post may vanish at any moment.

  22. #22
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    DougR

    That would work, but my consideable record of discussion with PeterR is that he will already have considered it, and come up with an entirely sensible solution.

  23. #23
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    Only just come across this post Peter, Absolutely stunning workmanship as always what a beautiful craft.
    Atb Terry.

  24. #24
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    Many thanks Terry, very kind. She now has quite a few miles on the clock and the corresponding number of scratches. Worse still, I managed to reverse my car over the outrigger beam last weekend at Coniston, smashing off the wave deflector, so that caused a bit of wailing and gnashing of teeth. However, a bit of 'invisible mending' this week has gone well so perhaps it won't be noticed. At least I have this record of how she looked initially and boats are no use if not used!

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