Horsepower???

[Shawn]

Hummmm...now I'm really confused lol. Just kidding. Sounds like I may be slightly underpowered with the 5 and a bit heavy with the 8. I've been in underpowered situations before fighting strong tides trying to get back on the inside and it's no fun. I'll give this s little more thought. Thanks for the input guys!

What prop do you have on the 5hp? If it isn't a high thrust prop that alone would be a big change for you and could make a big difference.

On my 23 I went from a Johnson 8hp 2 stroke, 2 cylinder to the Sailpro. Drove the boat very well and had plenty of power. I ran it with a Racor fuel filter inline and never had fuel issues.

As far as the charging system keep in mind it is only putting out 6amps at WOT. At more typically cruising RPMs its output will be lower. Still it is very nice to have. Motoring at night you won't be on a power deficit from nav lighting for example.

Shawn

[Shawn]

I too have been thinking about upgrading to a 9.9, specifically one with electric start and power tilt. Not lazy, just getting older and engine tilting could be an issue in the future. I am concerned about the extra weight though. Interesting in hearing from others about their experiences. 

I have a 9.9hp electric start, power tilt and remote control Suzuki on my Sabre 28. Wonderful engine and those extras make it fantastic to use.

However, with electric start and power tilt you are looking at 110 pound outboard at least. To hang that much weight on a 23 you will want to make absolutely sure your transom plywood is in good shape and maybe still reinforce it more if it stays in a slip. If you plan on trailering it with the engine I would reinforce it. You will absolutely need to upgrade your motor mount and that much weight on the stern would seriously alter the trim on the 23. That much weight on the stern of a 7900 pound 28' Sabre altered my waterline and I had to add about 80#s to the anchor locker to offset it and I had the advantage of being able to mount the engine to the centerline of the transom.

It could be done on the 23 but not recommended.

Shawn

[Blown Away]

Shawn,

Good info to know! Sounds like you have experience in this area. Curious to know if diodes have amperage ratings, and if so what happens if the amperage output of a alternator exceed the amp ratings of the diods on the controller, and solar cell? Also would those amperage ratings be in line with the output ratings of the cell or exceed them?

[Shawn]

Diodes do have amperage ratings (and voltage ratings) but the amp. rating doesn't apply in this case. Diodes are one way devices, they allow flow in one direction. Going from an alt. to a panel the diode will block all flow... as such there is no current (amps) passing through it. It doesn't matter if you have a 6a alt. or a 40 amp alt. No flow is still no current across the diode.

Where you could have a reverse flow is if you exceed the voltage rating, but diodes are typically rated at 500v or higher. An alt. isn't going to exceed that. About the only way to possibly have an issue is if you put a switch on the alternator and open/closed it while the engine was running. The collapse or creation of the field can cause a high voltage spike (think ignition coil) that might damage a diode but it will fail open and pass nothing in either direction. For an inboard user this is why it is a bad idea to switch off the main battery when the engine is running, it can damage the diodes in the voltage regulator in the alternator. Often diodes have additional diodes to shunt these sorts of spikes too.

Shawn

[Blown Away]

Thanks Shawn. I knew those diodes were there and acted like check valves but always thought they were probably rated at the same wattage/amperage output as the device and could get fried from a spike like the amperage output of an alternator. The possibility of damaging the device by switching it out of the circuit while the motor is running never crossed my mind. Bob I hope you are reading all of this, LISTEN TO SHAWN lol. Seriously I learned something new today, thanks for your input. Cool stuff!

[Craig Weis]

Shawn says " If it isn't a high thrust prop that alone would be a big change. "

What is high thrust? 

Does that mean push the most water with the least amount of rotations?
or
Spin the prop like crazy, just under cavitation, and move the most water possible?

What has to happen to make thrust? If it is an electric motor I think back to my years on an electric forklift with a 1,300 lb battery pac that is changed out every night and charged. Maximum shaft torque and hp and at ANY rpm above zero is available with electric motors. Not so with internal combustion engines that rely on climbing rpm's to make hp. Anyway as the rotar climbs out of zero rpm to max rpm the brass contacts on the speed control sizzle and burn and toss green copper sparks but cools down once the motor reaches the controlled rpm speed.

This is the same action that properly sized 'heaters' go through on number two motor contractors when starting three phase electric motors. These heaters glow red hot and go back to metal grey color once things are up and running. Full load starting, as it is, pulls the maximum amp's out of the battery pac at full load start.


Funny thing is I don't know what all that means but it is the reason why an automotive type automatic transmission changing engine or motor and shaft rpm's can never be used to drive a propeller in the water. No gear shifting. There was a story in YACHTING MAGAZINE explaining all this years ago but it went right over my head. I don't understand the science behind it.

Craig Weis.

[HeaveToo]

The alternator on an outboard isn't really worth much if you have any electrical load on the boat.  They type of cruising that I do I need better charging than that so I put a 100 watt solar panel on my bimini.  It runs through a Genasun GV-10 charge controller.  I keep my house bank, 230 amp hours, charged all the way up most of the time because of the solar.  This is even if I sit at anchor for a few days.

I have considered going to the high thrust prop for my outboard.  I have the 8hp with a regular prop.

[Bob23]

Heave, I'll pick your solar brain at the CBMWG version 2.0.
Bob23

[Shawn]

I knew those diodes were there and acted like check valves but always thought they were probably rated at the same wattage/amperage output as the device and could get fried from a spike like the amperage output of an alternator.

The amperage rating probably is based somewhat on the output of the solar panel but that doesn't matter for reverse current. Another example... a 10w panel puts out less than an amp. But you can plug that into a fully charged deep cycle battery that can put out *hundreds* of amps and the diode is still fine.

Shawn

[Shawn]

"Does that mean push the most water with the least amount of rotations?"

No, the opposite. Say an outboard has a 9" pitch prop.. the idea of that is it moves 9" of water each rotation assuming no losses. Something like the Sailpro has a 6" pitch prop as well as larger/fatter blades to grab onto the water more. My Suzuki is  4 blade 10" prop at 5" pitch.

"Maximum shaft torque and hp and at ANY rpm above zero is available with electric motors. "

Yup, electrics make max torque at 0 RPM. However, with no rotations on a prop you have no thrust to move a boat. EDIT: HP is *always* related to RPM so even an electric does not make max HP at 0RPM it makes no HP at 0RPM, just max torque. HP = (torque in ft/lbs x RPM) / 5252

"Not so with internal combustion engines that rely on climbing rpm's to make hp."

EDIT: internal combustion engines rely on climbing RPMs to make torque. HP always needs increasing RPM no matter what type of engine we are talking about.

This is part of why a high thrust prop can make a big difference. Say you have a 5hp engine.. it makes max hp at say 6000 RPM. If you have to high a pitch prop on it (on a slow moving hull) the engine may not be able to spin the prop above 3000 rpm. The engine might only be make 2 or 3 hp there and it won't drive the boat well. Put on a higher thrust prop (6" pitch) and now the engine will be able to rev up higher and make more power. End result is it will drive the boat better.

Best way to think of prop pitch is like gearing in a car. A higher thrust prop (lower prop pitch #) is like a lower gear, higher prop pitch # is like a higher gear.

A higher thrust prop will accelerate better (just like first gear) but on a planning boat (that isn't HP limited) it won't have as much top speed as a higher prop pitch (higher gear).

On a displacement boat top speed is limited by the boat. On a heavy boat that is harder to accelerate we want that lower gear to move the boat easier and to allow the engine to get into its power band.

"Funny thing is I don't know what all that means but it is the reason why an automotive type automatic transmission changing engine or motor and shaft rpm's can never be used to drive a propeller in the water. No gear shifting."

There is gearing but it is more like the final drive ratio in a car. I didn't see that article but I think it is basically that a multiple gear transmission isn't really needed. In a car you can't really get moving in 4 or 5th gear (at least not without roasting your clutch) but in a boat with a fluid connection you can get the prop spinning to at least start moving and then accelerate the boat.

Shawn

[Shawn]

The alternator on an outboard isn't really worth much if you have any electrical load on the boat.  They type of cruising that I do I need better charging than that so I put a 100 watt solar panel on my bimini.  It runs through a Genasun GV-10 charge controller.  I keep my house bank, 230 amp hours, charged all the way up most of the time because of the solar.  This is even if I sit at anchor for a few days.

I have considered going to the high thrust prop for my outboard.  I have the 8hp with a regular prop.

My Suzuki has a 12amp alternator which is pretty decent for a smaller outboard. That can be nice if motoring at night as it keeps everything topped up. But I totally agree about solar too, I have a 100w panel as well and that will keep me charged up and my fridge running all summer. Best thing to do is what the energy budget and get rid of incandescent lights as they use a ridiculous amount of power compared to LEDs.

Shawn

[HeaveToo]

Last summer I did a 12 day trip.  During that 12 days I never once plugged into shore power.  A lot of those days were cloudy with rain.

On days that I sailed I ran a stereo all day, autopilot for hours at a time, lights in the cabin (LED) and the LED anchor light.  I also ran the GPS, VHF with AIS, depth finder, and a few other instruments. 

On a few days I didn't go anywhere because of weather.  On those days I ran lights in the boat to read, anchor light at night, and I also plugged in my cigarette lighter sized inverter to charge my laptop.

I never got low on power.  On some days I had a full battery in the afternoon and my total electrical budget was running off of the 100 watt solar panel.

Coming from a boat where I ran a lot of power and only charged through a 30amp alternator on the diesel, I think that my energy budget is about the same on the Compac since I never have had refrigeration (this is the biggest energy killer).  I love the safety net of a large flexible solar panel.

I will say, if you can afford it and you want the best, go with a Soloban Panel.  There have been recalls on my panel for causing fire.  I would never leave my panel up for a long period if I wasn't around the boat because of the recalls.  I should be fine with the way I use my panel but it is still something to consider.

If you are going with a 100 watt panel or less, go with the Genasun GV-10 controller.  It is the best MPPT Charge controller on the market for smaller panels.  MPPT is the way to go for charge controllers btw.

Here is the best source I have found for information on solar panels:

http://www.pbase.com/mainecruising/solar_panel

http://www.pbase.com/mainecruising/solbian_solar_panel

http://www.pbase.com/mainecruising/solar_controller_testing

[Blown Away]

My Suzuki has a 12amp alternator which is pretty decent for a smaller outboard. That can be nice if motoring at night as it keeps everything topped up. But I totally agree about solar too, I have a 100w panel as well and that will keep me charged up and my fridge running all summer. Best thing to do is what the energy budget and get rid of incandescent lights as they use a ridiculous amount of power compared to LEDs.

Shawn

Wow!! Didn't realize a 100w panel was able to keep up with all mentioned. Im new to smaller boats and just haven't given solar much thought yet. Embarrassed too say that on my 32 I just start the engine and charge up. I actually have a fairly large panel in storage that's never been hooked up. What sort of battery banks are you guys charging with these 100w panels (types of batteries, amp hours, etc)? A world of knowledge here, so glad I joined this site!

[Blown Away]

What prop do you have on the 5hp? If it isn't a high thrust prop that alone would be a big change for you and could make a big difference.

On my 23 I went from a Johnson 8hp 2 stroke, 2 cylinder to the Sailpro. Drove the boat very well and had plenty of power. I ran it with a Racor fuel filter inline and never had fuel issues.



As far as the charging system keep in mind it is only putting out 6amps at WOT. At more typically cruising RPMs its output will be lower. Still it is very nice to have. Motoring at night you won't be on a power deficit from nav lighting for example.

Shawn

Shawn

I don't know yet what prop is on this engine. Just got finished rigging my trailer to pick up the boat a couple of states away, and will hopefully be heading out within the next week. I'll keep you posted. Thanks again for sharing your knowledge.

Karl

[HeaveToo]

I have two 6 volt GV2 Duracell batteries wired in a series to get 12 Volts.  They are 215 amp hours.

One of the biggest power consumers is refrigeration on a boat.  I have never had it because I always have access to ice where I cruise and get ice every few days.  After refrigeration, I have heard that radar is a larger power consumer.  Since I am not running those I think that my solar panel can more than catch up and keep up with what I run.  I don't run my inverter much because I worry about the drain on the batteries.

yes, when I had my Catalina 30, I used the engine to charge stuff.  That can be a mistake because you never get up to 100% while out cruising if you are charging that way.  If you have an idle day and run solar there is a change that you can get the full charge if you get a good amount of sunlight.

It is all about how you cruise.  Since my 23 does longer trips I need this.  If you are sailing from a slip and do one night or two night trips and then go back to the dock to plug in or if you go into a transient slip every few days you don't need a large solar panel.