Hey people - I currently have a 9.9 for my 23. I've heard somewhere that a good rule of thumb for a sailboats OB is 2 HP for every 1000 lbs of displacement. If my O'day is around 3k, that would come out to a 6HP motor. What are your thoughts? I think my 9.9 is too heavy, and although i believe "bigger is better" with engines, I have no plans on sailing around the horn anytime soon. Thoughts on going down to a smaller OB would be appreciated...
Outboard HP roll call
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I ran a 6 HP two stroke for years on my O'Day 23. Worked fine. I even used a 4 HP from time to time, and that was Ok, but not great. One day, I had the chance to get a Yamaha 9.9 HP 4-stroke for half price, still in the box. I used it for years on the '23. Yes, it is a bit heavy, but I didn't use a bracket on the transom for the engine, instead I mounted it in the transom cutout. It actually worked very well in the cutout. All the controls were right there, beside you. I just had to remember to turn the engine when I pushed the tiller to starboard, or the prop would hit the rudder (it never damaged the rudder, just made a whirring noise). Overall, the 4-stroke was fantastic; used a lot less gas and was very quiet. The extra thrust, especially in reverse, came in handy many times.
I really thought that R.O.T. was 2 HP/ ton of displacement, but can't seem to verify that at the moment. If that were true, however, your boat would require 3 HP. I know my 25' racer weighed 3000 lbs and 4 HP was very adequate. I wanted the light weight and the ability to easily remove it.
In the book "Ted Brewer Explains Sailboat Design" by (can't remember who wrote it--- Oh Yeah Ted Brewer) he charts required HP for boat w/ LWL of 20' and 1.5 tons disp.(close for you, I would guess) as needing 2.6 HP to reach 5 knots. In order to reach 6 knots - just above hull speed - required 5.7 HP.
The thing you gain with a little larger engine is the possibility of electric start and battery charging. Also, quicker response to direction change, stopping power, etc.
In the book "Ted Brewer Explains Sailboat Design" by (can't remember who wrote it--- Oh Yeah Ted Brewer) he charts required HP for boat w/ LWL of 20' and 1.5 tons disp.(close for you, I would guess) as needing 2.6 HP to reach 5 knots. In order to reach 6 knots - just above hull speed - required 5.7 HP.
The thing you gain with a little larger engine is the possibility of electric start and battery charging. Also, quicker response to direction change, stopping power, etc.
I have a 4 stroke 4hp on an inland lake. Works fine for me. I went with the smaller motor so that my wife could lift it. A 6 hp extra long shaft seems ideal for a 23.
It's not so much about overall HP - remember most small motors 6, 8, 9.9 hp are marketed for small fishing boats, dinghies, etc. which are, for the most part, planing hulls. The propeller pitch shipped with the OBs are higher, to allow the lighter boats to run faster at higher RPMs, and to get the boat on plane. With a sailboat, you'll never get her on plane, and she's heavier, so you want to run with a lower pitch and larger diameter prop, or something listed as a high thrust prop. This will allow the motor to run in a higher, more appropriate RPM range (limiting carbon build up from low run time/low RPMs), and will also give you more thrust, especially in reverse.
If you wanted to decrease weight, you could look for a lower HP "sail pro" model. These usually start about 6hp, and come with a long shaft or extra long shaft (25"), alternator, possibly electric start, and definitely a high thrust (low pitch, larger diameter) prop. With smaller trailer sailors in the 19-23 foot range, seems to me a 6hp with long shaft, high thrust prop ought to be just right.
Sage Marine sells the Sage 17 with a 2.5hp Tohatsu long shaft. I asked about more HP, and they said that they feel there's no need for higher HP, as the 2.5 pushes the boat at hull speed.
Brian
If you wanted to decrease weight, you could look for a lower HP "sail pro" model. These usually start about 6hp, and come with a long shaft or extra long shaft (25"), alternator, possibly electric start, and definitely a high thrust (low pitch, larger diameter) prop. With smaller trailer sailors in the 19-23 foot range, seems to me a 6hp with long shaft, high thrust prop ought to be just right.
Sage Marine sells the Sage 17 with a 2.5hp Tohatsu long shaft. I asked about more HP, and they said that they feel there's no need for higher HP, as the 2.5 pushes the boat at hull speed.
Brian
I would go further. Outside of the extra weight and the features you noted, the slightly larger motor has several other advantages.
First, you can throttle the larger motor back to provide the same speed the smaller motor would provide at full throttle. Less noise and vibration.
Second, engines require slightly more fuel (richer fuel mixture), above 75% power. The larger motor could actually surpass the smaller motors fuel economy at lower power settings while producing the same amount of power (speed) the smaller motor would provide at full power.
Third, If the motor can barely provide enough power to reach hull speed in no wind/calm sea conditions, you will have no reserve power or direction control should sea or wind conditions rise before you. There was a story I read recently of a guy offshore (the west coast, IIRC) who could make barely 1 knot returning to port because of too small a motor. The winds had come up, and coupled with beating head on into waves and wind, he was crawling along like a snail watching his fuel tanks empty, worried if he could make port before running out of fuel. He made it, but never wanted to repeat the exercise.
I would think real hard before downsizing that motor.
Good point. All the outboards I used had three-bladed props, pitched for thrust, not speed. The 9.9 Yamaha actually came out of the box with the long shaft and large 3 blade prop, specifically for sailboats.
I've posted on this topic before. I have a 9.9 Johnson on my V25. I would not run anything less. It does have the electric start, when it works and a rectifier to charge the batteries. In New England the tides and currents are startling. I fought for an hour and a half to cover what seemed to take 25 minutes to cover in the Cape Cod Canal. We were barely beating the people walking on the shore. 4knot current will have you in agreement that bigger is better. Sailmaster with the sea prop. The blade shape is the symetrical giving the same thrust in forward or reverse. 4hp is good for the lake but not river estuaries and the ocean.
I think the last response is getting to the real issue -- what kind of conditions do you expect to encounter? On a lake a smaller motor would do. Near the ocean with ties and currents, you may very well want something larger.
I have a 9.9 ultra long shaft on a 23 and in most conditions it's too much engine. But there have been one or two times I was glad to have it.
I have a 9.9 ultra long shaft on a 23 and in most conditions it's too much engine. But there have been one or two times I was glad to have it.
Many of the twin cylinder engines actually use the same basic motor for several different power ratings, with the only physical change being a larger or smaller carburetor to provide more or less power. The Johnson 5 HP has the same exact bore and stroke as the 6HP, 7.5 HP, and 8 HP, and they all weigh about the same. The 9.9 is the same basic motor as the 15 HP, again with the only real difference being a smaller carb. The Honda 7.5 is the same as the 9.8 and 15. The Mercury 6 HP is the same basic motor as the 8, 9.9 and 15. So unless your going way small, like less than 5 HP, your just buying a detuned motor for the same price as the bigger one, and they all weigh about the same.
Let me add my two cents. The 222 I acquired around the first of the year was offered with a virtually new Honda 5 hp. As best as I know, this particular boat has been small lake based for many years. During the "demo" sail the motor worked fine for the lake. That said, I intend to use the boat not only on the lake, but also out of harbors on the Oregon coast. That means tides, currents, and getting across harbor entry "bars". To my mind, 5 hp didn't have the extra power for ocean condition. So, I opted for an 8 hp Mercury long shaft with electric start. I think that this engine will give me a bit of "pad" in difficult conditions. Additionally, it will charge the boat battery when in use -- which the 5 hp Honda wouldn't do.
Agreed 100% Brian. I have a 23' and use a Johnson 6.6 with sailmaster long shaft and a three bladed low pitch prop. I had to add the 6" extension to the shaft and also the prop to make use of the hp to get up and go, rather than go fast. Works perfectly on Lake Huron without adding lots of stern weight.
Just this weekend, I put my 6hp on the O'day 192 to a bit of test. I motored home in plenty of wind and whitecaps, straight into the wind. Windfinder.com had a history graph for Sunday showing a bona fide 32mph gust around the time period I was motoring home with averages at around 25mph. I wasn't in any hurry, and I didn't feel like having a lot of motor noise, so I was maybe at 1/2 throttle, maybe 1/3 throttle. I had no problems. I still don't know what pitch and diameter my prop is, but I was running WOT the weekend before, just to see how it was doing. I can say that at WOT, the motor did not seem to be running fast as I thought it should be, which leads me to believe I have a relatively low pitch/higher thrust prop.
Wow. I retread that. Seems totally anecdotal and non-conclusive of anything
All I know is that the darn thing idles a heckuva lot faster than I think it should. Maybe it's time to visit the shop for a bit of adjustment...
Brian
Wow. I retread that. Seems totally anecdotal and non-conclusive of anything
All I know is that the darn thing idles a heckuva lot faster than I think it should. Maybe it's time to visit the shop for a bit of adjustment...
Brian
I have a 6 hp johnson longshaft. 2 stroke on my 22 it reaches hull speed at about half throttle . I havent been out in any extreme weather but in 4 and 5 foot swells on Lake Superior it performs just fine. I dont know the pitch of the prop but i agree with the posts regarding hull speed I really dont think the horsepower makes much difference wonder what the effect is on fuel economy? I hate to use my motor anyway so I wouldnt spend more on a few more hp .
I was just out in my O'day 192 tonight, with very light breeze. I concentrated on a few projects, so I didn't feel like hanking on the jib for a sail, but I did want to go on the water for a bit. I just motored around for a bit, and I fired up the GPS.
At idle speed, the 6hp Nissan 4 stroke was making 3.5mph, and WOT, we were doing 6.5mph.
A few notes, I always felt that idle was very fast on this motor, so when I got in to my slip, I busted open the cover, and adjusted the idle speed down to an acceptably low speed. And, I've often felt that this motor doesn't seem to get as fast as I think it ought to run at WOT. I hope that means it's got a higher thrust prop. I'm very excited about the slower idle speed, though, because I always felt I was going through the marina too hot.
Brian
At idle speed, the 6hp Nissan 4 stroke was making 3.5mph, and WOT, we were doing 6.5mph.
A few notes, I always felt that idle was very fast on this motor, so when I got in to my slip, I busted open the cover, and adjusted the idle speed down to an acceptably low speed. And, I've often felt that this motor doesn't seem to get as fast as I think it ought to run at WOT. I hope that means it's got a higher thrust prop. I'm very excited about the slower idle speed, though, because I always felt I was going through the marina too hot.
Brian
I always adjust idle speed in gear with the boat moving and the engine warm. Slowly adjust it down until it quits/barely runs, then turn it back up just enough that it keeps running. Adjust it just high enough so you can shift into reverse without quitting and that should be about right. I actually turn my own motors down even lower, if needed I can goose the throttle a bit after shifting to keep it going.
Regardless of the application, these are primarily fishing motors and are designed to run very slow for trolling in reverse, and it wont hurt them at all to do so. Just let them warm up first. Small two strokes can generally be idled down much slower than comparable 4 strokes, though a Honda 7.5 HP I had years ago could turn amazingly slow.
Regardless of the application, these are primarily fishing motors and are designed to run very slow for trolling in reverse, and it wont hurt them at all to do so. Just let them warm up first. Small two strokes can generally be idled down much slower than comparable 4 strokes, though a Honda 7.5 HP I had years ago could turn amazingly slow.
Thanks for your procedure, Anchorclanker. I was smart enough to know that idling in neutral and under load were two different things, so I did have the motor in gear as I adjusted the idle. She seemed to go between F-N-R well. I think I will tweak it just a little bit more tonight, in gear, in free water this time. I'll see if I can get a wee bit slower, and still keep running when I shift from Forward with actual inertia, to Reverse. Doing so while underway will likely put just a bit more load on...
Do you have any thoughts about WOT? I'm guessing I might take it in to a mechanic to check that, only because I don't have a clip on tachometer (like they have in the Seloc manual) and I don't know that I feel like buying one... In further consideration, 6.5mph (5.6knots) isn't so bad. Mother's Day weekend, I sailed in 20mph winds with a gust to 30, and she pushed through that headwind and chop just fine at roughly 1/2 throttle, albeit not at hull speed. It's not like we can get displacement boats to go too much faster anyway. In fact, for a 18.5 foot boat with overhang bow, I have, what, 17.5' waterline length, which gives me a theoretical hull speed of 6.45mph (5.61knots) so I guess she's driving at hull speed at WOT... That's not super efficient, but I seldom need to get anywhere at hull speed. I'm usually content to putter around such that the motor is on the quite side...
Overall, this motor is in extremely good condition. When I bought it, the oil and lower unit hypoid lube were both clear... so at least the PO changed it before I bought it But the plug was in good shape, too, and so far, it starts on the 1st or second pull every time.
Brian
Do you have any thoughts about WOT? I'm guessing I might take it in to a mechanic to check that, only because I don't have a clip on tachometer (like they have in the Seloc manual) and I don't know that I feel like buying one... In further consideration, 6.5mph (5.6knots) isn't so bad. Mother's Day weekend, I sailed in 20mph winds with a gust to 30, and she pushed through that headwind and chop just fine at roughly 1/2 throttle, albeit not at hull speed. It's not like we can get displacement boats to go too much faster anyway. In fact, for a 18.5 foot boat with overhang bow, I have, what, 17.5' waterline length, which gives me a theoretical hull speed of 6.45mph (5.61knots) so I guess she's driving at hull speed at WOT... That's not super efficient, but I seldom need to get anywhere at hull speed. I'm usually content to putter around such that the motor is on the quite side...
Overall, this motor is in extremely good condition. When I bought it, the oil and lower unit hypoid lube were both clear... so at least the PO changed it before I bought it
But the plug was in good shape, too, and so far, it starts on the 1st or second pull every time. Brian
I think u will find that u can reach and maintain hull speed in calmer conditions at less than wot at least thats the case with my 22 and giving more throttle just uses more fuel.
I was sailing my 22 across the inlet over the weekend. Once I found myself heading into the outgoing tide I realized I wasn't moving. The wind pushing me couldn't over take the tide and my motion came to a stop.
The tide was ripping so hard that the large can markers were nearly on their side.
I sparked up my 6 hp 2 striker and had no problems cutting through. I was running between half and three quarter throttle.
The tide was ripping so hard that the large can markers were nearly on their side.
I sparked up my 6 hp 2 striker and had no problems cutting through. I was running between half and three quarter throttle.
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