Just want to say thank you for all your Outboard Motor recommendations from my previous topic entry. I am thinking of a 5 or 6 hp model. Just two more questions: I suppose the 20" shaft length is better but I also notice that Tohatsu has a 25" length---which would be better? And what are the advantages for the alternator option offered on some of the motors? I do all my sailing on a Pennsylvania lake. Thanks again! John B
Outboard Motor Shaft Length and Alternator???
- Thread starter JCBRENN
- Start date
Lake Nockamixon in Bucks County Pennsylvania is the lake I sail on. So 20" shaft should be fine. Just wondering if an alternator option would be good----what would I need that for??? Thanks! John B.
Some alternator thoughts -
Outboard alternators provide 12 - 14 volts while your engine is running. Just like your car does. And like your car's alternator, the outboard's alternator only provides this voltage while the outboard is actually running. Not running = no voltage out.
There are two way an outboard's alternator can be useful. First, if you have a battery and electrical system (nav lights, cabin, lights et cetera), the alternator is hooked into this system so that, whenever the motor is running, it provides the power to run these lights and to re-charge the battery some.
Secondly, on a boat that has nav lights but no battery (I know it is not a good system, but I know some fishing folks who use this to get home on those days where they stay too close to sunset to be back before dark), the alternator will power the nav lights as long as the motor is running. No running motor = no nav lights.
If you think an alternator is for you, be sure to buy an outboard with one installed. Not all small outboards have one.
Some motor shaft length thoughts-
Motor shaft lengths and outboard motor mounting bracket position go hand in-hand-hand. Unless you are starting from scratch (i.e. installing a new bracket) or are willing to change what you have in the way of bracket position, you will need to work with the motor bracket mounting position you have. There does not seem to be a standard motor bracket mounting position on the transom. You see brackets mounted high, brackets mounted low, and brackets mounted every where in between.
Let's talk about what you want a bracket mounting position and shaft length combo to accomplish -
When you are actually motoring, you want the propellor to remain under water even if the boat is pitching somewhat. There is nothing more aggravating then not being able to make some needed headway into some waves or wakes when you need to because the prop is popping out of the water.
When you are sailing, the bracket is up and the motor is tilted clear of the water. You want the motor to stay clear of the water. Even when the boat is heeled way over. Heeling is only an issue on one tack - one tack raises the motor in the air, one tries to bury it in the water.
A longer shaft motor mounted on a low-mounted bracket will definitely keep the prop in the water while motoring, but it will not always get the prop out of the water while sailing - even when sailing flat and level. Heaven forbid what that combo does when heeled over to the motor side.
I use an extra long 25-inch shaft motor and a higher motor mount position. It is a great combination. Does all the good stuff above, plus has an extra benefit: while in the running position, the motor head (and thus the gear shift and throttle) are nicely raised above the back end of the boat in an easy-to-reach location.
I am not so sure that I would be happy with this same 25-inch motor mounted a bracket that was mounted lower on the transom.
I think a 20-inch shaft mounted on a bracket somewhere in the middle (heigth-wise) of the transom, is also a good workable combination.
Outboard alternators provide 12 - 14 volts while your engine is running. Just like your car does. And like your car's alternator, the outboard's alternator only provides this voltage while the outboard is actually running. Not running = no voltage out.
There are two way an outboard's alternator can be useful. First, if you have a battery and electrical system (nav lights, cabin, lights et cetera), the alternator is hooked into this system so that, whenever the motor is running, it provides the power to run these lights and to re-charge the battery some.
Secondly, on a boat that has nav lights but no battery (I know it is not a good system, but I know some fishing folks who use this to get home on those days where they stay too close to sunset to be back before dark), the alternator will power the nav lights as long as the motor is running. No running motor = no nav lights.
If you think an alternator is for you, be sure to buy an outboard with one installed. Not all small outboards have one.
Some motor shaft length thoughts-
Motor shaft lengths and outboard motor mounting bracket position go hand in-hand-hand. Unless you are starting from scratch (i.e. installing a new bracket) or are willing to change what you have in the way of bracket position, you will need to work with the motor bracket mounting position you have. There does not seem to be a standard motor bracket mounting position on the transom. You see brackets mounted high, brackets mounted low, and brackets mounted every where in between.
Let's talk about what you want a bracket mounting position and shaft length combo to accomplish -
When you are actually motoring, you want the propellor to remain under water even if the boat is pitching somewhat. There is nothing more aggravating then not being able to make some needed headway into some waves or wakes when you need to because the prop is popping out of the water.
When you are sailing, the bracket is up and the motor is tilted clear of the water. You want the motor to stay clear of the water. Even when the boat is heeled way over. Heeling is only an issue on one tack - one tack raises the motor in the air, one tries to bury it in the water.
A longer shaft motor mounted on a low-mounted bracket will definitely keep the prop in the water while motoring, but it will not always get the prop out of the water while sailing - even when sailing flat and level. Heaven forbid what that combo does when heeled over to the motor side.
I use an extra long 25-inch shaft motor and a higher motor mount position. It is a great combination. Does all the good stuff above, plus has an extra benefit: while in the running position, the motor head (and thus the gear shift and throttle) are nicely raised above the back end of the boat in an easy-to-reach location.
I am not so sure that I would be happy with this same 25-inch motor mounted a bracket that was mounted lower on the transom.
I think a 20-inch shaft mounted on a bracket somewhere in the middle (heigth-wise) of the transom, is also a good workable combination.
It's Nockamixon, the HP LIMIT for the lake is 15hp (for all boats)... prevailing winds from Spring to Fall, average about 8 knots. A short shaft would be acceptable. NO chop, very little wake.
I WOULD suggest an alternator if you can afford the jump in price though, since Nox doesn't have power at the docks. I WILL tell you though, that despite what might be said, charging doesnt' happen with the alternator until you hit about 3/4 to full throttle. Most alternators are really 3-6amp chargers. So you'd need to spend several hours running your motor to reap any reward of charging, no charging from dead flat happening unless you have LOTS of fuel. That being said, it works well to maintain a battery though. If you also add a small solar charger to your circuit, you'll have enough power to use running lights for a few hours each month, and never need to worry about draining your battery because of it between the solar and the outboard (adding a solar panel to mine this winter, maybe a 25-40 watter)... I have a bunch of draw on my boat, VHF, wind, depth, speed, and radio though, so keeping charge is a bit harder.
I suffer from similar issues up on Lake Wallenpaupack. Wally is a larger lake by about 6 miles more than Nox, but it's an unlimited HP lake (more chop), but they STILL do not allow for power at the docks. The advantages of Wally are, of course, a larger lake, and its perfectly acceptable to swim in the lake (a huge bonus), and there are islands to explore. Because the lake is privately held (power company lake) it doesn't suffer from "NO PARK" syndrome, where DCNR controls your every move like at Nox. If the distance to drive is the same, its Wally hands down (which is why I am up there).
Don't get me wrong, I spent more hours on Lake Nox than likely half of the people in the Marina there. My father and I had boats there for probably a better part of 20 years. I also used to tournament fish the lake, and became good friends with several of the fish commission (that was in the 80s though).
Anyway, yeah I think 20 inch shaft and a nice alternator would be like the most excellent options you can get for that lake. 5hp would also be quite sufficient, and still easy enough to lug around, and get you hull speed just fine.
If you get bored, and want crew, hit me up shnool @ yahoo Nox is about the same distance from work for me as Wally.
Also you are welcome to come sail with me (I'll crew you drive) from May to Oct. Sure it's not a Capri, but my guess is you'll have fun just the same
By the way, the Capri on that lake has to be one of the "sportier" boats there. I saw 1 or 2 J22s, and I know the sailing school had a Capri 25, but the Capri 22 would (in my opinion) be the best of speed/cruise/trailer for that lake. You probably frequently speed past most other boats there. As I recall the "common" boats there are Precision 21s, 18s, and the occasional big boat of a Rhodes 22, or Precision 23. Actually when we were there, there wasn't anything larger than a 23 (might have been a restriction of the marina though I don't recall).
I WOULD suggest an alternator if you can afford the jump in price though, since Nox doesn't have power at the docks. I WILL tell you though, that despite what might be said, charging doesnt' happen with the alternator until you hit about 3/4 to full throttle. Most alternators are really 3-6amp chargers. So you'd need to spend several hours running your motor to reap any reward of charging, no charging from dead flat happening unless you have LOTS of fuel. That being said, it works well to maintain a battery though. If you also add a small solar charger to your circuit, you'll have enough power to use running lights for a few hours each month, and never need to worry about draining your battery because of it between the solar and the outboard (adding a solar panel to mine this winter, maybe a 25-40 watter)... I have a bunch of draw on my boat, VHF, wind, depth, speed, and radio though, so keeping charge is a bit harder.
I suffer from similar issues up on Lake Wallenpaupack. Wally is a larger lake by about 6 miles more than Nox, but it's an unlimited HP lake (more chop), but they STILL do not allow for power at the docks. The advantages of Wally are, of course, a larger lake, and its perfectly acceptable to swim in the lake (a huge bonus), and there are islands to explore. Because the lake is privately held (power company lake) it doesn't suffer from "NO PARK" syndrome, where DCNR controls your every move like at Nox. If the distance to drive is the same, its Wally hands down (which is why I am up there).
Don't get me wrong, I spent more hours on Lake Nox than likely half of the people in the Marina there. My father and I had boats there for probably a better part of 20 years. I also used to tournament fish the lake, and became good friends with several of the fish commission (that was in the 80s though).
Anyway, yeah I think 20 inch shaft and a nice alternator would be like the most excellent options you can get for that lake. 5hp would also be quite sufficient, and still easy enough to lug around, and get you hull speed just fine.
If you get bored, and want crew, hit me up shnool @ yahoo Nox is about the same distance from work for me as Wally.
Also you are welcome to come sail with me (I'll crew you drive) from May to Oct. Sure it's not a Capri, but my guess is you'll have fun just the same
By the way, the Capri on that lake has to be one of the "sportier" boats there. I saw 1 or 2 J22s, and I know the sailing school had a Capri 25, but the Capri 22 would (in my opinion) be the best of speed/cruise/trailer for that lake. You probably frequently speed past most other boats there. As I recall the "common" boats there are Precision 21s, 18s, and the occasional big boat of a Rhodes 22, or Precision 23. Actually when we were there, there wasn't anything larger than a 23 (might have been a restriction of the marina though I don't recall).
He folks;
Unless I am mistaken -- unlike a generator, an alternator needs a battery to work. ( A generator has permanent field magnets)
Hershey
Unless I am mistaken -- unlike a generator, an alternator needs a battery to work. ( A generator has permanent field magnets)
Hershey
Everyday speech blurs many good technical definitions which we all use.Hershey said:
TECHNICAL DEFINITIONS:
Electromagnetic generators fall into one of two broad categories: DYNAMO and ALTERNATOR.
• DYNAMOS generate direct current (DC), usually with voltage or current fluctuations, usually through the use of a commutator.
• ALTERNATORS generate alternating current (AC), which may be rectified by another (external or directly incorporated) system.
The magnetic fields can be created by either a permanent magnet (no battery needed) or a separate electrical source (typically a battery).
You need a battery for an alternator to work. ( Or get started working). Unlike a generator (dynamo) where the magnetic field is created from the permanent magnet, in an alternator creates it's own electro-magnetic field. But, at the start there is no electricity to create this field. Once started, one could remove the battery as the alternator would be self sustaining as long as the motor keeps running.
Hershey
Hershey
An alternator differs from a dc motor in that it contains no permanent magnets. Instead, there are two concentric wound coils of wire within the alternator: a stator coil (the outside coil which does not rotate) and a rotor coil (the inside coil, attached to the alternator’s pulley, which does rotate). The rotor is also referred to as the alternator’s "field."
An electromagnet is created when current flows through the field coil. The strength of the magnet is directly proportional to the amount of current flowing through the field. As the rotor moves clockwise, the resultant magnetic field sweeps clockwise through the outer coil of wire, and electricity is generated in the stator coil. Since the magnetic field sweeps back and forth through the stator coil, an alternating current is produced. The alternating current has a frequency equal to the frequency with which the alternator’s pulley is rotating.
For this process to begin, the alternator’s field must start with some kind of current. Rotating the rotor coil itself does absolutely nothing, unless there is current flowing through the coil, producing a magnetic field. Thus, it is necessary to have the alternator hooked up to a battery to supply this initial current.
Hershey
An electromagnet is created when current flows through the field coil. The strength of the magnet is directly proportional to the amount of current flowing through the field. As the rotor moves clockwise, the resultant magnetic field sweeps clockwise through the outer coil of wire, and electricity is generated in the stator coil. Since the magnetic field sweeps back and forth through the stator coil, an alternating current is produced. The alternating current has a frequency equal to the frequency with which the alternator’s pulley is rotating.
For this process to begin, the alternator’s field must start with some kind of current. Rotating the rotor coil itself does absolutely nothing, unless there is current flowing through the coil, producing a magnetic field. Thus, it is necessary to have the alternator hooked up to a battery to supply this initial current.
Hershey