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      Abbreviated rules   07/28/2017

      Underdawg did an excellent job of explaining the rules.  Here's the simplified version: Don't insinuate Pedo.  Warning and or timeout for a first offense.  PermaFlick for any subsequent offenses Don't out members.  See above for penalties.  Caveat:  if you have ever used your own real name or personal information here on the forums since, like, ever - it doesn't count and you are fair game. If you see spam posts, report it to the mods.  We do not hang out in every thread 24/7 If you see any of the above, report it to the mods by hitting the Report button in the offending post.   We do not take action for foul language, off-subject content, or abusive behavior unless it escalates to persistent stalking.  There may be times that we might warn someone or flick someone for something particularly egregious.  There is no standard, we will know it when we see it.  If you continually report things that do not fall into rules #1 or 2 above, you may very well get a timeout yourself for annoying the Mods with repeated whining.  Use your best judgement. Warnings, timeouts, suspensions and flicks are arbitrary and capricious.  Deal with it.  Welcome to anarchy.   If you are a newbie, there are unwritten rules to adhere to.  They will be explained to you soon enough.  

Joakim

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  1. How to build large format display

    My solution was to use AdvanSea Multi 400 displays, which have big digits and are very cheap. I added two to my Raymarine setup. I can see them very well in almost all conditions from 20 feet where I sit while steering. I made my own connection box, which transforms seatalk into NMEA 0183 with some unconventional sentences added. E.g. distance from starting line is send as depth (range +200 m to -10 m), TWD + TBS percenatage as total distance, heading as trip distance etc. In the image BSP is 8.95 knots, SOG 8.96 knots, heading 280, TWD 55 and TBS is 17, which means 117% thus 17% over target. The Raymarine display in the middle shows TWA and TWS, the latter of which is very hard to read in many conditions. I have had this setup since 2012 and it has worked very well.
  2. The classic Nexus/Silva wind transducer PCB is extremely simple and it has just a few basic components, which can be easily found from electronics parts suppliers. Missing one signal could be due to missplaced optoreader. They should be 1-1.5 mm from the ball. Or the ball colouring could be worn out.
  3. Lead crystal batteries?

    As far as I know BMS is mainly used to balance cells. The 12 V LFP batteries have no external access to the four cells it has in series so they can't be balanced or have some internal balancing. I don't know how well this works in a long run, but they are probably the most common LFP in sailboats. It's quite common to have 13.8-14.0 V charging voltage at the batteries with an alternator. That should still be quite OK for LFP. Usually the alternators are 60-120 A and do not need a current limit for protecting LFP from too high charging currents unless a small LFP is used with a big alternator. Usually FLP allows 1-3C charging current. I have a 60 A alternator and it will charge my 180 Ah LA at full 60 A for about an hour when staring from 50% SOC. It will automatically limit its output due to coil resistance and limited magnetic field. I do think alternators are designed to survive outputting full current (= not reaching target voltage). Shore power chargers typically charge to 14.4-14.8 V and keep that voltage 2-4 hours untill they go to float state, which is in the 13.2-13.6 V range typically. The only problem here regarding LFP is possibly overcharging during the 2-4 hours of CV. A cheap solution for this would be adding a diode, which would drop the charging voltage by 0.6 V and prevent overcharging. Possibly you would not get 100% SOC, but quite close to that. You do need a system to cut off at some voltage (say 11-12 V) in order not to destroy permanently your LFP. The system I linked uses that only for house usage, thus it doesn't need to be high current one and is rather cheap.
  4. Lead crystal batteries?

    What makes LFP not drop-in friendly? I know there are some possible problems like too high float charging or overcharging while motoring for longer periods, but these are not a problem in all cases and can be fixed rather easily.
  5. Lead crystal batteries?

    LFP is not a drop in replacement? Several of my club mates have bought this kind of system: https://lime-power.se/sv/teknik/enbankslosning/ It's in Swedish, but you can see the schematics only has fuses a shunt and a battery guard, which shuts off the house usage, but allows starting and charging. They use these: http://www.cactusnav.com/alfatronix-pt100-powertector-solid-state-battery-guard-932vdc-100a-p-13622.html No changes in charging system, but the system includes a battery monitor. From what I have heard that seems to work OK. I don't know how well the batteries will last or are they used to their potential with that simple solution.
  6. Lead crystal batteries?

    Aren't Firefly's about as expencive as the cheapest LFP at the same nominal capacity?
  7. Spinnaker cloth Airx v Superkote

    According to North Sails diagram S2 is to be used from 10 to 20 knots (depends on the angle a bit) TWS and down to about 80 deg AWA. With this usage you will get up to about 12 knots AWS. And during a broach you will get about 20 knots AWS in 20 knots TWS.
  8. Spinnaker cloth Airx v Superkote

    OP asked about medium runner, which S2 is, not light running, which would be S1.5 according to North Sails naming. I Have a 0.5oz S1.5 and 0.75oz S2 at 90 m2 size. I can't really tell much of a difference how they float or fill, especially in10 kts, when I have no problems flying my S2. OP did not tell us how many spinnakers he has and what will be the actual role of S2. I don't have a S3 nor S4 (I do have an assymetric that I could use reaching or any heavy air), but even if I did I can think of many cases where I would not want to change the spinnaker when a medium run turned into heavy run or a reach. If I would now buy a new S2, I would be looking more on a more tolerable than a lighter cloth. But maybe it's just me misusing S2. Anyway it has worked very well while reaching, even below 50 AWA. I feel it is faster than the assymetric I have on a reach.
  9. Lead crystal batteries?

    The Trojan premium line deep cycle flooded battery I linked earlier is a practical product and seems rather cheap for what it's claimed to tolerate. Here is a datasheet: http://www.trojanbattery.com/pdf/J200-RE_Trojan_Data_Sheets.pdf 1600 50% DOD cycles, 1000 80% DOD cycles and 800 100% DOD cycles. 200 Ah at $300. How much does the lead crystal batteries cost? For them they claim better cycle life up to 80% DOD, but Trojan does better at 100%. Here are also some other Trojan deep cycle batteries: https://www.altestore.com/static/datafiles/Others/Trojan RE Product Guide 2014.pdf Note that the flooded ones have clearly the highest cycle life, not GEL nor AGM.
  10. Spinnaker cloth Airx v Superkote

    That's 0.75oz (although more in reality as all other 0.75oz). Why would that be way too heavy for a S2 and what problem would there be from it being heavier than the minimum. I use my S2 quite often for reaching as well and I don't think 0.5oz would like that. Quite often the wind gets heavier and again you are happy to have a bit more forgiving cloth. Bainbridge says 8 knots AWS for AIRX500 and 12 knots for 700. You get more than 12 knots AWS quite easily, if you need to do some reaching.
  11. Lead crystal batteries?

    You need to charge the batteries when you reach the end of the usefull capasity. For a normal LA that is around 50% SOC (for a true deep cycle 20-30% or even lower) and for LFP 10-30% SOC. Most often you have considerably smaller nominal capacity with LFP due to price and higher usefull capacity with the same nominal. My LA battery is not deep cycle, but it still has survived my use for 7 season + unknown number of seasons with the previous owner. We cruise 3-6 weeks + some weekends per season + some racing. When we are cruising we get shore power 2-5 times a week. Some days there is no wind and we motor. The longests legs we do are 48 hours, but mostly we sail just during daytime. I haven't used the engine for just charging during the last few years. 250 50% DOD cycles is at the limits for a normal LA battery. E.g. Exide Dual (non-AGM) has just that: http://www2.exide.com/Media/files/Downloads/TransEuro/ML/Exide_Marine leaflet 2015_Europe_EN.pdf The best deep cycle LA can do more than 4000 50% DOD cycles so the range is huge and LA can have equal or even better cycle life than LFP. I have quite low power consumption and very seldom need do 50% DOD cycles with my 180 Ah battery. I'm also not that worried about keeping the batteries at 60-80 % SOC for longer periods. Batteries (non-AGM) in my cars seem to last 10 years despite the voltage is typically just below 12.30 V when measured after 10+ hours parking. So they seem to be around 60% SOC most of the time due to short distances I typically drive (seldom over 20 minutes). I have a 50 W solar panel on the roof under the boom. Around here I get only about 10 Ah/day out of it. But it is enough to top up the battery while the boat is unused for a week. I very seldom use the shore power at our home marina. Not always even after sailing with 70% SOC while coming back.
  12. Lead crystal batteries?

    Moonduster, I don't know what kind of cruising you are talking about, but you will need to charge the same amount of Ah with both battery options. Charging with engine it's not worth it to charge beyond 80% with LA, since charging current starts to get lower.
  13. Lead crystal batteries?

    You did notice I was comparing 180 Ah LA to 90 Ah LFP? When you have used your normal range, LA would be at 50% SOC and LFP at 10-30%. So once you have charging problems, you still have 50% of 180 Ah left with LA, but only 10-30% of 90 Ah for LFP. You are shortening the life of your LA, but you can do it and keep using navigation lights and instruments for a much longer time.
  14. Lead crystal batteries?

    Here is a LA battery that can do close to 4000 cycles to 60% DOD and 2000 to 80%: https://www.gs-yuasa.com/jp/products/pdf/VRLA_SLC_SLE.pdf Probably not cheap. This reasonably priced flooded one claims 1600 cycles to 50%: https://www.altestore.com/store/deep-cycle-batteries/flooded-lead-acid-batteries/trojan-spre-12-225-j200-re-12v-solar-premium-line-flooded-battery-p40522/ My aux battery is a 180 Ah "super heavy duty", flooded, most likely a starting battery. It is from 2010 or older and still works fine. It very seldom goes below 60% SOC. I would start the engine for charging at aournd 40-50% SOC, but that takes from 100 SOC around 40 hours, which we seldom do. A 90 Ah LFP would cost 3x. Would it last 3x longer (20+ years)? It would have about the same usable capacity, but much less reserve capasity. Say you are close to lower end of the usable capacity, but for some reason your engine won't start. With LA you still have 90 Ah left, but with LFP only 9-27 Ah based on your limit. Quite often with LFP installation you don't even have a separate starting battery, which further lowers your reserve.
  15. Prop size for an Erickson 35

    Maximum possible diameter is probably not the best option in this (and many other) cases. That will lead to very low pitch to diameter ratio. 0.5 is already low and you need to go lower than that if the diameter is more than 15". That will lead to poor efficiency. The calculator you linked is propably the very simple one that also can be found as an Excel sheet. It is not accurate at all. It can work in some cases, but I would not trust that. It uses very simple formulas for estimating optimum propeller size and also for estimating the power needed. It would suggest a 13.2 x 6.6 two bladed propeller. That is not far from the current 12x6, which is not working well at all. Any decent propeller estimation is done using propeller curves, which show the thrust, torque and efficiency at the operation condition. I used such for the estimated 14x8.