#1
IP: 173.180.27.222
|
|||
|
|||
Prop size.
I have a 1972 Columbia 30 which has an atomic 4 with a Walter V-drive and 2:1 ratio. Under the coil, the engine bears the stamp UJ-5 UF (The U and F are overlapped) as in my attached photo.
My question is regarding my prop. It is a 15 x 9 RH prop and the C-30 owners manual called for a 16 x 9 RH prop. Does my prop have to work harder than a 16 x 9 prop to move the boat 9 inches forward, and result in more load on the engine trying to push the boat, or do I simply have less push from the prop? On a separate note I have been suffering the issue of shutdowns after 1 hr. of cruising and read the notes re. adding a ballast resistor before the coil to protect it and the EI from getting fried. I used Neil's spreadsheet formula and bought a 1.2 ohm resistor. I was going to put the resistor on the plus lead going into the coil but have read elsewhere on the forum that when other circuits are also using this plus terminal to supply 12v to whatever, that the resistor needs to go on the minus lead (black) between the coil and the EI Doesn't this mean that the resistor is now after the coil and not doing what it intended for? Surely if I fit the leads from the plus side of the coil to the new resistor, and the other end of the resistor to plus side of the coil, only the coil will be affected by the resistor . Any advice appreciated. |
#2
IP: 71.118.13.238
|
|||
|
|||
Shrek, the best way to choose a prop is to check where you are with a tach and a reasonably well tuned engine. You should achieve red-line at WOT and be able to cruise in the intermediate ranges. This is a basic on any marine power plant.
You need to establish the target RPM for your app then you can go from there either up or down in pitch and diameter. You can check the load with a vac gage and a set RPM point for actual loads on the engine. It will take about the same power to move your boat 6kts no matter the prop. IE lets say it takes 15HP to move you at 6kts with either prop you mentioned. However they will achieve the 15HP load at different RPM's and throttle (vacuum) settings. And yes there will be a slight variation in frictional drag on bigger blades using a tiny bit more or less power. Example, my boat cruises at 5.9 kts with my Indigo prop and at the same speed with my 12x10 2 blade. They are both absorbing the same power from the A-4 at 5. kts however the 2 blade does so at 1550 (6" of vac) RPM's and the Indigo at 2,100 (10" of vac) RPM's. The engine is just having an easier time making the 15HP at higher RPM which eases the crank load and engine stress. Dave Neptune |
#3
IP: 71.118.13.238
|
|||
|
|||
Coil
How many power take offs are on the positive post? And what is the voltage at the post when up and running?
Dave Neptune |
The Following User Says Thank You to Dave Neptune For This Useful Post: | ||
Shrek (05-05-2016) |
#4
IP: 107.0.6.242
|
||||
|
||||
Since any advice is appreciated
Mine is to get all that stuff off of coil+ and run separate circuits. IMO the ignition circuit is too important and sensitive to be shared with voltage robbing accessories.
|
The Following User Says Thank You to hanleyclifford For This Useful Post: | ||
Shrek (05-05-2016) |
#5
IP: 24.152.132.65
|
||||
|
||||
Quote:
Quote:
edit: And FYI while I agree that all those wires on the coil are a fright (and more common than anyone wants to admit), the only things that 'rob' voltage are poor connections and wire insufficient (too small) for the load combined with circuit length. That's basic electricity 101. Size the wire properly and there's no concern. If the subject is difficult or confusing just let us know, we can help. references for those so inclined: ABYC E-9.14e (1) through (4) National Electric Code 210.19(A)(1) FPN No. 4 Blue Seas treatment on voltage drop https://www.bluesea.com/resources/53...e_Sizing_Chart
__________________
Neil 1977 Catalina 30 San Pedro, California prior boats 1987 Westsail 32, 1970 Catalina 22 Had my hands in a few others Last edited by ndutton; 05-05-2016 at 11:27 AM. |
#6
IP: 173.180.27.222
|
|||
|
|||
Here is a better view of my attempt to understand my coil wiring. (see new photo) from the + terminal we have the red wire going to the EI module in the Distributor. From the minus terminal we have the black wire going to the EI module in the Distributor and the grey wire which should be going to the Tach.
Then also attached to the + of the coil we have 3 purple wires which I assume, due to their colour, are Ignition related and my ignition sw., is inside the cabin, the Starter sw. in the cockpit, and the Alternator in the engine compartment. I also have an Ammeter. I believe the other red wire on the coil + comes from the Alternator. I have not traced all of these wires yet but I do know that one of the purple wires is terminated on the ignition switch, which also has a red wire and a black wire on it. Presumably these are a Batt +ve and a Ground. My new rigging is being tweaked up today as the installation is finalized and the running rigging is changed out today as well. I will try to find time to trace all of these wires and see where they all go. Then I will report back on my findings. Forgive my ignorance but surely if I leave all of these wires bunched together on one end of the new resistor and attach the other end of the resistor to the coil +, would not the coil be the only thing affected by the added load of the resistor? I followed the directions given on this forum and input the test results into Neil's calculator and deduced that I needed a 1.1 ohm resistor, but was only able to find a 1.2 ohm example which I hope will do the job. Thanks as always for any advice given - now, where should I put that resistor??? Gordon Foster (Shrek) |
#7
IP: 24.152.132.65
|
||||
|
||||
Quote:
To your knowledge, has this coil EVER been involved in a shut down?
__________________
Neil 1977 Catalina 30 San Pedro, California prior boats 1987 Westsail 32, 1970 Catalina 22 Had my hands in a few others |
The Following User Says Thank You to ndutton For This Useful Post: | ||
Shrek (05-06-2016) |
#8
IP: 173.180.27.222
|
|||
|
|||
Thanks for the quick reply. This coil has never shut down and the resistor will be added before I take the boat back home to my own marina, 4-5 hours away. The other coils which I believe shut me down have all been deep sixed, as they can no longer be trusted, even from their cooled down resistance readings.
I hope this resistor addition will be the end of my shut down woes and I would like to rewire the a-4 with Moyers rewire kit very soon, should help th tidy up the mess. I will report my findings later. Busy finishing off the splendid re-rigging job. Photo's will follow. Got it done by the best guy in the area with 30 yrs. rigging/racing experience. GF |
#9
IP: 24.152.132.65
|
||||
|
||||
After your rigging is done I recommend analyzing the ignition circuit for wire size. You have 5 wires on the coil '+' post and at least one supplies the power to the system via the ignition switch. You'll need to determine what the loads are on the remaining four, total the loads and insert the number and the circuit length into the voltage drop calculator found in the ABYC and USCG Standards forum category.
Since you used our calculator you can figure 3.4 amps for the engine ignition (EI system) and 3 amps is a safe estimate for the alternator excite wire. Beyond that you'll have to trace where the wires go and determine their loads if any. Your goal is no greater than a 3% voltage drop on the entire circuit.
__________________
Neil 1977 Catalina 30 San Pedro, California prior boats 1987 Westsail 32, 1970 Catalina 22 Had my hands in a few others |
The Following 2 Users Say Thank You to ndutton For This Useful Post: | ||
Administrator (05-05-2016), Shrek (05-06-2016) |
#10
IP: 107.0.6.242
|
||||
|
||||
Quote:
|
#11
IP: 209.52.88.140
|
|||
|
|||
Very busy day today and tomorrow doing the running rigging, adding mainsail reefing and lazy jacks. Thanks for all the support and I will report back when I can get a breath in.
GF |
#12
IP: 24.152.132.65
|
||||
|
||||
You're not alone
Gordon, here are a few pictures from this forum showing that your coil stack is pretty common. I'm posting these uncredited to protect the innocent.
Something I wanted to point out in your recent picture, something to think about when you get around to rewiring, something to avoid. The circled area shows wires run over a sharp edge, a virtual guaranty of a future chafe-through and circuit failure.
__________________
Neil 1977 Catalina 30 San Pedro, California prior boats 1987 Westsail 32, 1970 Catalina 22 Had my hands in a few others |
The Following 2 Users Say Thank You to ndutton For This Useful Post: | ||
Administrator (05-06-2016), Shrek (05-06-2016) |
#13
IP: 107.0.6.150
|
||||
|
||||
No Need to Protect The Innocent
The picture in the middle is my boat, Destiny. I did not mean to suggest that no wires other than the feed to coil+ and the black EI wire should be on the coil. There are numerous other wires on both coil terminals that need to be there - but they should not be big load carriers such as pumps/blowers etc. On my coil, the picture in the middle, on coil- we have the black wire from the EI and the sensing wire from the tachometer (almost no load). At coil+ I have the red wire from the EI, the pink wire from the "R" terminal on the solenoid, the supply wire for the tachometer, the power feed from the resistor, and voltage sensing wire (the white one) so I can monitor voltage at coil+. This voltage remains steady because no significant loads are fed from coil+ except the ignition.
Last edited by hanleyclifford; 07-13-2016 at 08:23 PM. |
#14
IP: 107.0.6.242
|
||||
|
||||
BTW, Neil is right about those wires running over the head and down over a corner - between chafing and dry out from heat they could have a short life. If you can do it, it is best to re locate the coil off the engine to another location, as in the case of two out of three of the "innocent".
|
The Following User Says Thank You to hanleyclifford For This Useful Post: | ||
Shrek (05-06-2016) |
#15
IP: 12.17.168.100
|
||||
|
||||
As others have noted, I too am a big fan of using a buss bar to take the "load" off of the coil terminals.
Then you can have a nice clean coil install without the "Christmas Extension Cord" effect hanging on your coil...
__________________
-Jerry 'Lone Ranger' 1978 RANGER 30 |
The Following User Says Thank You to roadnsky For This Useful Post: | ||
Shrek (05-06-2016) |
#16
IP: 107.0.6.242
|
||||
|
||||
Jerry - How do you feed/sense the tachometer?
|
#17
IP: 70.192.2.116
|
|||
|
|||
Circuit Protection
An alternative to the buss connection is to use a fuse panel, like the Blue Sea 5015 for AGC fuses, or the 5028 for ATOs. This gives the ability to provide protection for each branch circuit based on its wire size.
|
The Following User Says Thank You to tac For This Useful Post: | ||
Shrek (05-08-2016) |
#18
IP: 12.17.168.100
|
||||
|
||||
The - Terminal of the coil fed from the buss bar.
__________________
-Jerry 'Lone Ranger' 1978 RANGER 30 |
The Following User Says Thank You to roadnsky For This Useful Post: | ||
Shrek (05-08-2016) |
#19
IP: 66.183.144.82
|
|||
|
|||
Bus bar in my immediate future
7am at my local marine store tomorrow I will be standing in line for a Blue Sea Systems, bus bar. It will be fed by the main ignition source wire and have all of the stuff on my Christmas Tree coil + terminated on it. It will also have the new wire gong down to the coil + via the 1.2 ohm resistor which will be the only wire directly attached to the coil +ve. (along with the EI +ve.) The coil -ve. will have the Tach. wire and the minus of the EI.
Will post photos as proof of my intended innocence asap. The rigging job has gone well but been delayed by 20 - 30 MPH winds these last 3 days. All standing rigging is replaced, all bronze turnbuckles replaced with S/S and all running rigging being completed tomorrow (wind permitting). Also adding Lazy jacks, and 2 reefing lines for the mainsail, all new mast wiring and LED lighting, new Windex, new flag halyard on the Stbd spreader, and a new VHF antenna and wiring as well. Ah well - It's only money ! Thanks, to everyone for the excellent help and guidance along the way (so far). Gordon Foster |
#20
IP: 66.183.144.82
|
|||
|
|||
Fingers crossed.
tomorrow will see the end of the new standing / running rigging job and also , hopefully the end of the premature shut down issues.
I used Neil's ballast resistor calculator for my EI and coil and the figures were as follows Coil resistance with minus wires removed was between 2.9 to 3.1 ohms, so we averaged it out to 3.0 ohms. Voltage in system at 1000 rpm was 13.77 volts Voltage at cruising 2000 rpm was 13.86 volts. When input to the calculator spreadsheet we arrived at 1.1 to 1.2 ohms ballast resistor requirement. The differences in the figures were due to instability in my multimeter's readings, but the different figures still arrive at basically the same value for the ballast resistor no matter what. I have today removed the Christmas Tree wiring and installed a Blue Sea Systems Bus on the wall of the engine room to feed the circuits which were on the coil +ve. and then I ran a new purple wire from the bus bar through to the coil +ve via the resistor. The positive going to the EI is the only other wire on the coil +ve. The coil negative side carries only the feed to the EI, and the tach wire. Hopefully this will be the last of my issue. The engine started and ran fine at the dock - time will tell. It did sound strangely smoother though. Perhaps a figment of my imagination ??? Gordon. Last edited by Shrek; 05-10-2016 at 12:28 AM. Reason: grammatical error |
#21
IP: 107.0.6.242
|
||||
|
||||
Quote:
|
The Following User Says Thank You to hanleyclifford For This Useful Post: | ||
Shrek (05-10-2016) |
#22
IP: 209.52.88.203
|
|||
|
|||
Yes. As I said in my post first at 1000rpm and second at 2000 rpm to represent cruising approx.
|
#24
IP: 24.152.132.65
|
||||
|
||||
Hanley, before this goes too far, it was my interpretation that Gordon's voltage measurements were made to determine a suitable resistor for his system. That is, prior to installation of a resistor.
__________________
Neil 1977 Catalina 30 San Pedro, California prior boats 1987 Westsail 32, 1970 Catalina 22 Had my hands in a few others |
The Following User Says Thank You to ndutton For This Useful Post: | ||
Shrek (05-10-2016) |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
what size prop to use | whiskey wings | Drive Train / Propellers | 12 | 10-25-2015 12:54 PM |
What size prop? | smp | Drive Train / Propellers | 15 | 09-12-2012 08:35 AM |
bolt size for prop shaft coupling | tartansailboat | Drive Train / Propellers | 34 | 09-27-2011 11:08 PM |
Proper size and pitch prop for 74 C&C33 MkI | kwalters | Drive Train / Propellers | 6 | 10-16-2008 05:24 PM |
Prop size | Sailwood | Drive Train / Propellers | 8 | 05-06-2005 02:55 PM |