My 8 hp, 2-stroke Tohatsu is 18 years old. I'm not sure I trust it anymore and I can't find anyone to work on it. So I'm thinking about a new outboard. I have a few questions:
1. Do I need a long-shaft or a short-shaft outboard? I'm not sure what I have now. The boat has the standard motor mount that pivots up and down.
2. Will a 6 hp 4-stroke be enough to push a Com-pac 23/3? I'm on a lake so I don't have to worry about currents or tides. (An 8 hp motor is $700 more expensive and a lot heavier.)
3. I've read that I can get a prop that has more torque than the standard prop that comes on a 6 hp Nissan or Tohatsu outboard. Does anyone know about props?
Thanks
6 HP 25" shaft will more than likely be plenty on a "inland lake" - The Great Lakes are another entirely different scenario. If you ever intend to trailer to a coastal or Great Lake site - I would consider upgrading for that event to at least an 8 HP High Thurst.
Hi GF:
I also have a Nissan (same as Tohatsu). Mine is a 1988 8 hp 2 stroke and I wouldn't trade it for the world. Sure, it's 24 years old but starts first time everytime.
Why don't you trust it? Has it crapped out on you? I think 95% of the outboard problems are due to gas issues. I always use premium gas with stabilizer and always use fresh gas.
Definitely get a long shaft. And I think a 6hp would be fine with no tides or currents to contend with. My 8 hp has pushed my 23 into opposing tides and winds just fine. Not too fast but it pushed the boat.
Can't help you with props but I'll be watching this thread for someone who does!
bob23
I use the Tohatsu 25" 6hp SailPro on my 23/3 with no problems at all on the ocean. I've motored into 25knot headwind without issue. Replaced an 8hp Johnson 2 cylinder 2 stroke.
Be sure you get the SailPro edition however as it has the elephant ear high thrust prop on it. I've seen reports of others using the non-Sailpro 6hp version on similar sized boats and being unhappy with it. The wrong prop keeps the engine from getting into its power range.
Shawn
Shawn:
Does the prop have a different name other than elephant ear? I may look into that.
bob23
Bob,
Tohatsu has two versions of the "High Thrust" prop that fits on their 6hp engine. From testing I saw in a thread when I was considering the Sailpro the "elephant ears" version was considerably better on a displacement hull. I think the part number is: 399B645121M
http://www.internetoutboards.com/partdetail.asp?id=719
The prop comes standard on the "SailPro" model.
Don't think it will fit your 8hp engine though. You should be able to find a 6" pitch prop for your engine if you wanted to.
Shawn
It's all in the pitch. Power VS Speed. Or should I say low end vs top end.
I have the tohatsu 6hp sail pro extra long 25" shaft on my 19. I have used it in some pretty strong tides into a strong head wind and it doesn't even break a sweat. I understand a 19 is a much smaller boat, but it reaches hull speed at 25% throttle. It's all in the high thrust prop. I think it would be fine for a 23'.
There are lots of threads about outboards here. Just non about props that I'm aware of.
Bob, you really should look at your prop. A little more low end torque can make a lot of diffence. How do you know your prop isn't for some 20' aluminum John boat?
I love my SailPro too! works great my 19, I would think it would be super on a 23 as well.
-Ray
Billy:
I really don't know; that's why this is so interesting. My Nissan is a long shaft but I'll look into the prop issue before spring launch, which seems to be delayed this year.
But I do love the dependability and simpliciy of my 8 hp. Everytime I get tempted to buy a new 4 stroke, I remember the "start on the first pull" feature. I do confess to being an extreme motor (and truck) maintenance freak!
bob23
Quote from: Bob23 on May 10, 2012, 08:38:04 PM
Hi GF:
I also have a Nissan (same as Tohatsu). Mine is a 1988 8 hp 2 stroke and I wouldn't trade it for the world. Sure, it's 24 years old but starts first time everytime.
Why don't you trust it? Has it crapped out on you? I think 95% of the outboard problems are due to gas issues. I always use premium gas with stabilizer and always use fresh gas.
Definitely get a long shaft. And I think a 6hp would be fine with no tides or currents to contend with. My 8 hp has pushed my 23 into opposing tides and winds just fine. Not too fast but it pushed the boat.
Can't help you with props but I'll be watching this thread for someone who does!
bob23
Thanks to everyone for all the information. Good stuff!
I'm a bit concerned about the old Tohatsu because I can't get anyone to service it. I second your concerns about fuel so I do use premium gas with a stabilizer. It starts after the second or third crank (electric start). I guess I'm just a worrier by nature.
For everyone who uses the "sailpro" are you also using the "standard" adjustable motor mount?
Mine is a gerlick or similar. I think it is rated for 60lbs maybe 80 and adjustable. I do think the sail pro is right about 60lbs.
And Bob, the new ones have the "start on 1st pull" feature as well. Heck, even the admiral can start it!
There is a Tohatsu dealer in St. Petersburg, FL named Star Marine and you can get one for about $1,300 bucks. They're light, dependable, super efficient, and plenty strong. The sail pro has a really nice tilt so when tilted up the pro clears the water easily. The shaft is long enough, I usually don't even need to lower the mount (unless it is really rough).
Quote from: gfspencer on May 10, 2012, 08:14:03 PM
My 8 hp, 2-stroke Tohatsu is 18 years old. I'm not sure I trust it anymore and I can't find anyone to work on it. So I'm thinking about a new outboard. I have a few questions:
1. Do I need a long-shaft or a short-shaft outboard? I'm not sure what I have now. The boat has the standard motor mount that pivots up and down.
2. Will a 6 hp 4-stroke be enough to push a Com-pac 23/3? I'm on a lake so I don't have to worry about currents or tides. (An 8 hp motor is $700 more expensive and a lot heavier.)
3. I've read that I can get a prop that has more torque than the standard prop that comes on a 6 hp Nissan or Tohatsu outboard. Does anyone know about props?
Thanks
I have a short shaft, I sail on an inland lake and the short shaft is fine for the most part, except sometimes if I'm solo sailing and jump up front to lower a sail while the motor is going, the prop actually lifts up out of the water. If I was buying new, I'd go ahead and spring for the long shaft motor.
I think wind is a bigger issue than tide. If the outboard has enough power to get you to hull speed a bigger engine won't change that. As such tide isn't really a factor... going with the tide or going against the tide your hull speed (speed through the water) does not change.
Shawn
What do our boats weigh? I see that the displacement is 3,000 lbs. I'm not sure how that figures into boat weight. The reason that I ask is that I've been e-mailing Online Outboards and they say that the 6 hp Tohatsu Sail Pro is too small for a Com-Pac 23/3. I don't want to have a 8 hp outboard (90+ pounds) hanging of the back of my boat.
Displacement is boat weight. It is a measure of how much water you displace to keep it floating. Add onto that all the weight of your gear and your passengers.
The SailPro is fine for the 23/3. There are a number of 23s with the Sailpro.
Shawn
Displacement is the amount of weight of water a boat will displace while floating. Boat manufacturers use the term incorrectly as boat weight. That has always been a pet peeve of mine.
Chris
Chris,
The weight of the water displaced by a floating boat is equal to the weight of the boat (and everything in it).
The boat is pushing down by 3000 pounds, 3000 pounds of displaced water is pushing back up. Opposing forces are balanced, the boat is floating.
Shawn
The bigger prop is almost a requirement for efficiency and low revs. I just went across the gulf stream with a 4 hp mercury long shaft. When the seas moderated to 4' we were able to complete the last half of the crossing against 15 mph headwinds in a 23' Compac. The sailpro model would be the best choice.
I found (and then subsequently lost) a marine designer calculation that gives the horsepower requirement for a displacement hull. When I did the calculation for a ComPac 23 it came out to 5.4 HP and I'm fairly sure that has some condition safety factor included. I would have already swapped my very heavy 9.9 for a SailPro, but waiting for the next planned road trip to do so. Thought it would be BEER 2012, but a wedding may keep that from happening.
Weight was mentioned. For the tohatsu mercury motors it's the same power head until you get to the 8 hp. With the single cylinder motor one person is able to handle the motor even while the boat is afloat when you want to move the motor onto the dingy. The motor bracket on the boat is almost as important as the motor choice compare carefully. Fair winds
I have an older Tohatsu 9.8 with the large diameter and very short pitch prop. Full throttle over revs by about 200 rpm and hits about 6.6 mph. Burns lots of gas compared to about 5 mph. 8 HP with short pitch prop should work fine even in the wind.
For five years I sailed in Galveston Bay with a 20 year old Tohatsu 9.9 hp 2-stroke extra-long shaft and very much appreciated the added horsepower when I was fighting a tidal current plus wind. At other times it was overkill...but very nice to have when I needed it. When I retired and returned home to Colorado I left the old smoking 2 stroke behind and replaced it with a modern 4 stroke Tohatsu 8 hp as I now sail much smaller lakes without the tidal currents. The 8 seems more than adequate and just a standard long shaft...in place of the old 25 in extra-long...works just fine without the high chop I used to encounter in Galveston Bay. So the bottom line is that the motor that the CP-23s needs depends quite a bit on where you sail. I actually think a 6 hp would be fine where I am right now but the Admiral refused to go with a non-electric start motor so I was forced to go with an 8 hp instead of the 6 hp I would have preferred.
Fair winds,
WindRush CP-23/III
When I bought my CP19 in February it came with a 9.9 electric start OB. The PO had been using it in the Mississippi river and thus needed the extra horsepower. I read that the 19 needed 4-6 hp to be happy. I ran the calculations and came up with the follwong:
3 knots require = 1.1 HP
4 knots require = 2.6 HP
5 knots require = 6.2 HP
6 knots require = 8.8 HP
7 knots require = 14.0 HP
Since I am in NE Arkansas my local venues will be lakes. If I happen to the Gulf I still won't be looking at significant tidal currents
so I was figuring on downsizing to 2.5 or 3.5 HP. Does this sound about right for those out there with 19's?
My biggest concern is the weight of the current OB.
Going Back to gfspencer's original question:
2. Will a 6 hp 4-stroke be enough to push a Com-pac 23/3? I'm on a lake so I don't have to worry about currents or tides. (An 8 hp motor is $700 more expensive and a lot heavier.)
I calculated HP requirements for a CP 23 to be ...
2 knot 0.7 HP
3 knot 2.5 HP
4 knot 5.9 HP
5 knot 14.0 HP
If these calculations are correct, a 6HP OB should push a 23 about 4 knots. Is this consistent with other owners experience?
If these calculations are correct, a 6HP OB should push a 23 about 4 knots. Is this consistent with other owners experience?
Not my experience. With my 9.9, lake conditions, I can achieve 5.5 knots with the throttle about 40% open. 80% gets me over six and WOT doesn't do much better than that with hull speed being 6.02 for a 23. Can't tell you what the developed HP is at 40%, but doubt that it is anywhere near 6.
Interested to know about your calculation. As mentioned in an earlier post I had found a calculation for HP requirement for displacement hull. It was 5.4 HP for a 23, and that would take the boat to at least hull speed.
The big consideration for me is weight. Removing and replacing the 104 lb. 9.9 for a tow requires me, if alone, to disconnect my truck from the trailer back it up to the motor, remove it, with difficulty and lay it down, then line up and reconnect the truck. It takes at least two strong people to do it without using the truck, my wife does not qualify. Additionally all that weight affects the trim of the boat. It is a sailboat. I'm more concerned with proper trim than to have enough emergency HP to get me through some condition I may never see.
I had a 4 and a 6 for my Columbia 24 challenger. It had a displacement of 3900 lbs. Normally we would choose the four, because once sailing, we could lift the motor, put a plug in the well and lay the motor on its side in the well. Much harder to do with the six. 4 hp pushed the boat along fine.
Here's the calculation site on Pocketyachts
http://sites.google.com/site/pocketyachtcruising/sailing-references/sailboat-math
Fawsr,
GO HOGS! I'm originally from Fayetteville. Nice to see a fellow Arkansan on here.
I used to have a yamaha 2.5 hp 15" shaft on my 19 that worked fine with me. And that was with some fairly decent currents here in the gulf. The only 2 problems was the yamaha clogged the carbs anytime the gass was more than a week old. And I used stabil. The other was the 15" short shaft. Couldn't go forward.
2-3 hp will be more than fine for a 19 in a lake. Plus it is lighter!
Quote from: Tim Gardner on May 15, 2012, 07:49:20 AM
Here's the calculation site on Pocketyachts
http://sites.google.com/site/pocketyachtcruising/sailing-references/sailboat-math
Yep, that's the one, thanks.
Just redid my calc, comes to 5.14 @ design displacement and 6.09 with the added weight that the calc suggests. That is for the 23 theoretical hull speed which is 6.02 knots, which i never travel at, fuel use for that extra half knot is not worth it.
Still planning to drop to a six for the weight difference,
I'll send you the formulas I used this evening. On the road right now. Like you, my concern is weight & balance. At any rate looks like a 2.5 or 3.5 would do fine for me.
"If these calculations are correct, a 6HP OB should push a 23 about 4 knots. Is this consistent with other owners experience?"
No, I can hit hull speed with my 6hp SailPro.
The numbers for the 19 also ignore hull speed. 14hp will not get the 19 to 7 knots as that would require getting it up on a plane. The Sailboat Company tried a 40hp engine on a 16 and it wouldn't plane with that.
Shawn
I can hit hull speed easily with my very old Evinrude 2 stroke 8 hp. Since we do have strong current/wind combinations I like the power. The dealer who sold me the motor told me that 2 strokes were meant to run hard and that we sailors always have problems because we never do that. So over the years we almost always run full or near full bore for a bit. If I run full the boat digs a hole so 3/4 throttle is about it.
The Evinrude has a standard prop-it takes a lot of throttle in small spaces - turning around in a marina for instance. It also burns a gallon an hour at hull speed creating fuel storage problems on long cruises.
We will have to replace the motor one of these days - That 6hp Sailpro looks like quite a bargain with electric start and alternator for under 2 k
The formulas on the link provided are configured differently than mine, but came up with the same results. So I'm looking at a 2.5hp - 3.5hp range OB for my boat. Not at all concerned with being able to maintain hull speed. Just enough hp for putting it in and taking it out and a little forward progress when needed.
I bought my sail pro at Star Marine in St. Pete for under $1,350. He is as cheap as anybody. Doesn't have elec. Start though. The new models have the gear shift on the front too.
When we purchased our Com-Pac 23/3 it came with a long shaft 4 HP 4 stroke. We were surprised at how well it pushed the boat along. Stopping the boat wasn't as impressive. We have sold the 4 HP, sold a '52 Lightwin 3 HP and will sell our 8 HP 2 stroke Mariner as soon as we find a good deal on a Sailpro.
Last year I swore I would never use the Mariner again as it seemed to choose the wrong times to fail to start with anything less than 10 pulls. This was after a good carb rebuild. This spring I disassembled carb and let it soak in carb cleaner for a week. Well now the darn thing starts every time and seems to be apologizing for its previous bad behavior.
Still I like the 6 HP Sailpro and plan on purchasing one soon. Battery charging, 4 stroke and high thrust props are a good combination for our kind of sailing.
Mike and B
i have a 6hp sailpro that will push my 2500lb+ displacement horizon cat at hull speed at less than 1/2 throttle. i bought it because the engine has a battery charger but id be glad for a 4hp and the decreased weight if they sold a 4 with a charger. i think the rule is you cant push it faster than hull speed in the water but you might need the extra power to go into more and more wind.