Sadler 25 conversion..

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  • 20 Oct 2021 10:11
    Reply # 11656791 on 8800878

    I finally got to the boat last week for my last sail of the season.

    First I calibrated the log. I marked a 1/2 mile track on the chartplotter down the middle of the river and went backwards and forwards with the throttle fixed at 5 kts following Ueli’s instructions.
    I then did the sums. 

    It will come as no surprise to anyone that Arne was right!
    (and apologies Arne for my taking issue in my ignorance, with your doubting of my initial figures).

    According to my calculations the actual speed through water with 5kts showing on my log, was 4.45 kts, ie the paddle wheel is over reading by 11%.
    IF this margin of error remains the same at higher speeds, it would suggest that my actual speed through water at the 6.1 kts I previously reported corrects to a little over 5.4 kts.

    This at least puts my claims into the realms of the possible, as opposed to the absurd as per my previous post! 

    Last modified: 20 Oct 2021 10:15 | Anonymous member
  • 03 Oct 2021 22:25
    Reply # 11137696 on 8800878

    Thanks Ueli,

    I was hoping to do the test and sneak in a couple of days sailing this week, but frustratingly gales are forecast..

  • 03 Oct 2021 08:14
    Reply # 11136500 on 8800878

    hi paul

    Paul Gardham wrote:

    …(am I right in thinking that if I run a measured distance in both directions then take the mean time that will account for any current?)

    no, you don't need the mean time. you need the mean speed.
    you have to calculate the speed in both directions first. then you take the mean value. (this will give a faster speed than you average time calculation, as in a counter current you will loose more time than you win in the opposite direction…)


  • 02 Oct 2021 23:46
    Reply # 11136036 on 8800878

    Being a relative novice I just thought these figures were good, I hadn’t realised they were outrageous.
    Had I known I’d certainly have been sure to check the accuracy of my log before posting (all I’ve done so far is notice that at slackwater my chart plotter and log are pretty close).

    I will do as you suggest and check my log against a measured distance and a stopwatch!

    (am I right in thinking that if I run a measured distance in both directions then take the mean time that will account for any current?)

    …..then I’ll report back

  • 02 Oct 2021 19:40
    Reply # 11135715 on 8800878
    Anonymous member (Administrator)

    I don’t doubt that your report is correct in the sense that you read and report the numbers correctly.

    However, three factors still make me sceptical:

    • ·         I have never been on board a sailboat with any rig which sailed faster than the theoretical hull speed when fully closehauled  -  in the Sadler 25’s case 5.87kts. A speed of 6.1kts is no less than 4% above hull speed.
      I know my last two boats can go 8% above the hull speed, but that is on a beam reach. Fully closehauled, my Ingeborg only makes 80-87% of the hull speed.
    • ·         Thirty years+ as a maintenance engineer (electronics) have taught me to be sceptical to any measured numbers, whether being presented on analogue or digital gauges. I suggest you motor at a fixed speed over a measured distance and use the stopwatch to calibrate the log.
    • ·         That video shows that your boat sails well, but at that short waterline (5.84m) and at a suggested speed of 6.1kts, I would have expected more serious stern waves. To me the speed looks like ‘good, normal’ speed on that leg.

    I would say that an upwind speed of 5.5kts, or even 5.0kts would be very good. I, for sure, would have been very happy with those numbers.


    Last modified: 02 Oct 2021 19:44 | Anonymous member (Administrator)
  • 02 Oct 2021 19:03
    Reply # 11135667 on 8800878

     Hi Arne,

    I’ve just uploaded a video to my YouTube channel Junk Rig BooTwo

    it shows BooTwo sailing close hauled over a slightly foul tide at 6.2 then 6.1 knots on the log.

  • 26 Jan 2021 10:23
    Reply # 10033480 on 8800878

    Hi Folks,

    Next on my list of winter projects is building a windvane.

    I bought a Hebridean kit from John Flemming three years ago and haven’t got round to building it until now.

    I know a few of you have experience of this design, so wanted to ask if there were any modifications you might recommend.


  • 27 Nov 2020 23:18
    Reply # 9390588 on 8800878

    Hi David,

    I was just curious as to whether a hatch so close to the partners would be a no-no for structural reasons. Having a hatch would be terrific for ventilation, though if not advisable I suppose fitting an ‘air only dorade’ would be an option..

  • 27 Nov 2020 20:32
    Reply # 9390357 on 8800878

    I have the same kind of chainplates, and have left them in place against the remote possbility that they may be useful for tying something to. They don't seem to get in the way.

    As regards the forehatch, is it really necessary? Perhaps as emergency egress on a large boat in case of engine or galley fire, but otherwise it's a hole in the boat that might leak. If it's over the heads, wouldn't a ventilator be enough? 

  • 26 Nov 2020 17:38
    Reply # 9388657 on 8800878

    Hi folks,

    With BooTwo ashore for the winter I can now turn my attention to the remaining jobs to be done.

    I’d left the existing pointy rig hardware in place and now want to remove it all.

    With regard to the Chainplates (which on Sadler 25’s are bolted to the main bulkhead and come up through the side decks), should I leave them in place so that deck and main bulkhead remain tied together?

     I could just grind off the tab to which the shrouds were previously attached thus avoiding stubbed toes, but I would prefer to remove them altogether. 

    With my new mast through the old fore hatch position, I am thinking of re using the size 50 Houdini hatch I removed.

    Could I site it between the Main Bulkhead and Ringframe which is at mast partners? (ie directly aft of where it used to be)

    If so I could beef up the area by running longitudinal timbers either side of the new cutout, bolted fore and aft to ring frame and main bulkhead.

    As ever I’d appreciate your thoughts



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