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Frank

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Posts posted by Frank

  1. 2 hours ago, Addem said:

    Are these the same engineers who said “it’s strong enough” before?

    the rapid changes in forces between the foil section and bow section on those foiling boats must be mental at 20knots. 

    It must be a real head scratcher to model the load cases for these boats, there would be so many variables to account for. I would imagine the instantaneous loads from slamming into waves could at times be horrendous, like hitting the boat with an outsized sledge hammer.  Its amazing they last the distance at all, its a real tribute to the designers engineering skills.

    Many years ago a colleague related a story whereby Boeing sales reps were touring the world visiting prospective customers for the  787 dreamliner. Since there was a lot of suspicion about an all carbon fibre airframe they took a sample piece of the fuselage on tour so they could show how strong it really was. Customers were given a sledge hammer and invited to hit the structure as hard as they liked. One asian airline had a giant who didn't say much but was there just to swing the hammer, apparently it just bounced off !  with a satisfying "ping"

  2. On 22/11/2020 at 8:51 AM, marinheiro said:

    a thumbsuck rule for total re-engine cost for an "end to end" shaft drive replacement is double the engine cost (for a new engine). Could be a little less depending on how much you can do yourself. A saildrive replacement will be a little less than that factor

    Yep, agree with that, anecdotally I heard of a 34 footer where the instructions were " Replace the engine and send me the bill"

    50K later !

  3. I agree 2flit, years ago I had experience  designing repairs for airframes and based on that I'm confident the mast would not be significantly weakened.

    I measured up last night and the attaching screws are 4mm at 70mm spacing there is probably 80 to 100 to holes to drill and tap, so I'm more put off by the amount of work involved than any structural concerns. Also it wont do much for the cosmetics unless you're a colander :-)

    The sailmaker was concerned that a free standing luff would move around too much and generate chafe on the stowed mainsail particularly if you a carried the rig for a day or more. I pulled the trysail (sic) out of its bag and unsurprisingly it presents as brand new, I'm sure it never been hoisted in anger. Matt of IT has been helpful and the plan is to remove the track and ensure

    1. There is a 50% reef point in the main and 

    2. If practical modify the trisail so it will fit in the main track and ensure it is cut so as to clear the stacked main.

    Although the rig is well engineered I'm sure the sail would be far more secure in the main luff groove than on the tri sail track.

     

  4. These modern AC boats must present a fascinating head game for the team modelling the fluid dynamics. I'm guessing the hull is in some sort of ground effect and there must be an endless list of hydro and aerodynamic factors to optimize at 50 knot +.

     

     

  5. On 20/11/2020 at 8:36 AM, Black Panther said:

    I spent most of my working life presenting low offers. What i observed was silly low offers were less effective than "reasonable but a bit light".

    The silly offer would just piss the vendor off and make the rest of the negotiations much harder  . I found it better to start near where you want to end up. Then when you get a counter offer (won't happen if you start too low) say " I love your boat and would pay that if I could, but this is all I have".

    But what would I know. 

    Good words there.

  6. Some good possibilities there thanks Carpe Diem, I will discuss these with the sailmaker.

    BP sorry  I haven't explained the situation well but basically the track needs to be moved further away from the mainsail luff groove. The track extends from below the gooseneck almost to the second spreaders and is fixed with screws at 150 mm intervals hence re-positioning it involves  a lot of new holes, the mast height is 51 ft. We want to retrofit batten cars with external rollers but a test fit shows the rollers will foul tri sail track.

     

    Chrs

  7. I have a situation where I need to move the tri sail luff track on the mast, doing so will involve adding yet more fastener holes which  I would prefer to avoid.

    I have heard of a tri sail arrangement  where the luff is free standing using spectra as a luff rope. The sail is then hoisted on the main halyard and secured somehow at the foot.

    Does anyone have experience with this or has seen one set up ?any advice appreciated, I will check with the local sail maker as well.

     

    chrs

  8. Quite a few of the glass D28's had osmosis, dare I say it they are known for it (with due apologies to D28 owners past and present). Osmosis is not the big bogeyman it once was but it would be worth enquiring if it has had any remedial treatment in that area. I know of a local all GRP one that sold this week for somewhere around 20k I think. All uup if the wooden top is mint,the engine has been upgraded, the sails, running and standing rigging are in good to very good condition and the accessories are good then 20K would seem good value to me.

  9. With the new AC designs looking to turn on a dime does anyone  think there will be more boat on boat action than with the catamarans ? This action adds to the drama and if you can force errors  such as a fluffed turn it could be a powerful attacking or defending strategy. Most commentary is that the foil arms would  make this dangerous for both vessels and that it would be best to stay out of trouble. My sense is that we will see relatively more close manoeuvering than in Bermuda.

     

     

     

  10. Does anyone have a preference for using a shouldered rigging pin vs one secured with split pins at both ends ? My thinking is the former is better since one less split pin equals one less failure point.... thoughts ?

    Secondly should the split pin always have a washer behind it ? on our boat  the forestay top pin is not shouldered and there is no washer behind the split pins  it just doesn't look "Proper"  but maybe I'm just being a Nana, the tangs are aluminium.'

    Let me know what you think but the Forestay pin is slated for replacement with a shouldered one.

    Chrs

     

     

     

  11. 14 hours ago, 180S said:

    I do love the Vendee challenge, the best of yacht racing since the demise of the AC to flying machines.

    will be interesting to see if the foils are going to go the distance, would seem they are a mean ace in a rough seaway, wouldn’t the foil be an irregular drag ?

    Did wonder why they went so far NW when there was such a good breeze almost abeam for the southerly heading, maybe just making as much of the Westering that needs to be done.

    Wouldn't  you classify the new gen IMOCA boats as flying machines ? there is not much of the hull in contact with the water when they are at pace :-)

  12. I like the icons for the new gen boats the winglets, makes them look like  ice sliding penguins, well after a few gins maybe :-)  Its going to be an epic race and its fascinating to see how sailing technology continues to evolve just when you think they might have run out of ideas.

  13. A mate has a Don Senior 36 yacht with an old school twin car mainsheet traveler, its not a captive bearing type but rather it has four ball bearing "Wheels" on each car. I'm not sure of the brand maybe Cleveco or Ronstan ? . The wheel axle is also the inner race of the bearing which has worn so the bearings are now loose and probably close to failure. The axle shaft is swaged at each end.

    Does anyone have experience in repairing these or suggest where parts might be obtained ? 

    Of course replacement with an unobtainium Harken CB unit is the ultimate fix but that would be north of 2K I would imagine.

    Chrs

     

     

     

  14. I am involved  with one boat in the Tamaki Estuary on a pile mooring (38 Ft) and another on a swing mooring at Cocklebay (Carpenter 29). Like ( I suspect) many owners I have tried many AF options over the years but never finding a silver bullet solution.

    I got frustrated with the thicker paints as they were so intolerant of hot and/or windy weather, I was always thinning them to get coverage and a half decent finish.

    Eventually I tried  Hempel's which seems no better or worse than the  others in terms of performance but it is way less viscous and  rolls out easily almost like a single pot enamel. It doesn't seem to mind hot temps or wind and so  I find I get better and more consistent coverage. The tin is 5L which does the C29 with a little  to spare, while  38 ft vessel needs 6L. I use a mohair roller with a decent pile to carry the paint anything suitable for oil based paints should hang together.

    I have heard much discussion as to how many coats to apply and certainly there is a view that the thicker the finish the longer the interval between re-application. For myself I haven't found any benefit beyond two coats and sometimes just one good coat ! 

    PS:  I have no involvement with Hempel's or the retailer :-) I'm sure there are other brands which have similar characteristics.

     

     

     

     

     

     

     

     

  15. On 21/09/2020 at 9:36 AM, Steve Pope said:

    Chewing gum did it a few years ago, I bought a lot of info from him with anchorages marked, cruising guides, and a huge amount of useful notes, chart drawings, CD's etc etc. I would on-sell them to anyone interested. pm me if interested ??

    Thanks Steve, I will get back to you on that depending on how it all goes.

  16. 21 hours ago, splat said:

    Get hold of Jim Dilley - Environment Canterbury Harbourmaster, extensive experience cruising Fiordland and sub-antarctics in summer and winter. Ring him at Ecan. I'm sure he would love to chat about it.

    A good suggestion thanks for that !

  17. With a cruise to Fiji next year perhaps  a bit 50:50 due to covid, Fiordland in the summer could be a plan B.

    I presume Late Feb/March is the best time weather wise and that the direct route via the top of the NI is the best, but would appreciate any input from those who have been there and done that.

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