Is 6 hp enough?

[Robspan]

There is a 26D in my yard, and the owner needs to repower. I've been singing the praises of my Tohatsu 9.9, but he wants something that weighs less. The 6hp Tohatsu xl shaft supposedly only weighs 59lbs, as opposed to the 9.8 at 93lbs, and I have to admit that's a substantial difference. I told him about this forum but he doesn't "do" computers so I told him I'd ask.

I remember a lot of posts from owners who are happy with their 6hp's. My question is whether anyone with a 6hp has ever found it inadequate, for instance, against high wind and seas?

 

[Sumner]

On our first trip with our Mac the 8 HP Honda wouldn't start and we put the 5 HP Nissan (4 stroke) from the dingy on and used it for the 5 days we were out on a lake. It took us back to where we had been anchoring into 20-25 mph winds one afternoon and wasn't at full throttle. We never used full throttle to get to hull speed. No experience with currents though.

On our last 28 day trip the Honda started and ran and we used it the whole time we were out when we needed an outboard. Of course we never needed to run it at full throttle and I couldn't tell any difference using it over the Nissan.

One should remember that these outboards have torque and HP curves over their rpm operating range and if you don't have the right prop on you might be making less HP with a 8 or 9 HP because you never can get in the the rpm range that produces 8/9 HP and might only be making 5/6 HP at the rpm you are running even if you are at full throttle and not be any better off than if you had a 5/6 hp that had the right prop on.

On the Nissan I had re-proped it with almost the highest thrust prop I could find and I also have gotten a prop for the Honda that has been re-pitched so that it produces more thrust than any prop that is now available.

We need a new outboard so we can get electric start so that Ruth could start it in an emergency and I'd go with a 5/6 HP if I could find one with electric start, but I can't so it will probably be one of the 8/9 HP like the Honda, Yamaha or Nissan/Tohatus's.

c ya,

Sum

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[Capt. Kermie]

If the guy is mounting it semi-permanently and leaving it on the transom I don't see what difference an extra 30# is going to make?? It may be an extra stuggle when first mounting but once done it is done, no more struggles. I sail in the PNW and currents are a regular challenge here so the 9.8Hp would be my first choice. I have seen sailboats failing against the current and eventually going backwards so HP is not something I would skimp on. Besides the extra HP makes the difference between having to wait for slack tide or going when you are ready. I hate timing my trips for slack tide but I still do it even with 50HP because the Admiral says so.

 

[Capt. Kermie]

On our first trip with our Mac the 8 HP Honda wouldn't start and we put the 5 HP Nissan (4 stroke) from the dingy on and used it for the 5 days we were out on a lake.
One should remember that these outboards have torque and HP curves over their rpm operating range and if you don't have the right prop on you might be making less HP with a 8 or 9 HP because you never can get in the the rpm range that produces 8/9 HP and might only be making 5/6 HP at the rpm you are running even if you are at full throttle and not be any better off than if you had a 5/6 hp that had the right prop on.

On the Nissan I had re-proped it with almost the highest thrust prop I could find and I also have gotten a prop for the Honda that has been re-pitched so that it produces more thrust than any prop that is now available.

c ya,

Sum

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Not to hijack the thread, but as soon as you put the smaller dinghy engine on the big Mac the prop is not of the diameter and pitch to push that big lug because it was set for a light dinghy so of course one is not going to get full HP from it, likey a lot of slippage. How does one measure the rpms on these small engines anyway? Mine did not come with a tachometer and nor do I think others do.
The re-pitching sounds like a nice idea, something I should consider for my 5hp honda dinghy engine to make the little inflatable go faster but I don't even know if I am in the right rpm range now without a tach. Should I just get the little prop repitched an extra inch and hope for the best? I'd like the little dinghy to scoot a bit faster, even if it is only an extra 3-5mph, that will be enough.

 

[Robspan]

Capt. Kermie,
I think the boat will be trailered a few times a year, and when he does, he wants to take the motor off. I don't trailer mine unless a storm is on the way, so if it was me, I'd get the bigger motor.

We don't have much tidal range down here on the Gulf, so for the most part, the currents don't run very fast. I think the main concern is against wind and seas.

Sum, it sounds from your experience like a 6 with a low pitch number (6") would work. Good luck finding a 6 with electric start. If you do find one, please let us know.

 

[MrBill_FLL]

IMHO,
The key is keeping the prop in the water... not so easy in a short wave chop. (BTDT). (and it only takes a few minutes to burn up the impleller doing that, then the motor overheats, then its game over for that o/b...)

next will be the prop pitch. - not cheap to have a custom prop recurved (figure $250). but if the reason was fuel savings, it could be done. ( & yes I've spun prop hubs on smaller (9.9hp) ob's trying to push a bigger open fish in)

-A better answer for your friend is moving the trl axle back 12", and mount a bigger motor, and be done.

really no reason to pull the ob off the stearn unless its a tongue wt issue.

-OTOH, I'd try it...

 

[Sumner]

I have the prop on the dingy pitched for best results on the Mac as it is our backup motor. With the prop that came with the Nissan on the dingy it would plane.......


.........with one person, but not two. Since 90% of the time or more there would be two of us in the Zodiac I figured re-pitching for best results probably wouldn't hurt the dingy and might actually help with 2 or more of us in it. I haven't tried the dingy with the new prop, so don't know if it will still plane or not with one person.

One difference between your M and our S and D's is that you have a planning hull and we don't. I'd like to know how much throttle some of the guys with an S or D have had to use in situations like you have. Francois has an 8 hp yamaha I believe and is north of you, but I'm not sure if he posts here or not.

On the rpm thing I haven't looked into that, but tachs are sold for motorcycle engines that have 1 to 4 cylinders, so I'm sure there would be something out there.

c ya,

Sum

 

[Sumner]

IMHO,
...............next will be the prop pitch. - not cheap to have a custom prop re-curved (figure $250). but if the reason was fuel savings, it could be done. ..........

Bill we got a new 9 X 9 prop for the '90 Honda 8 HP for $80.00 and the repitch to 8 was $15.00 for a total of $107.00 with shipping.

http://www.midwestpropeller.com/

Good to deal with on the phone and fast service. He said he could pitch it lower than 8, but recommended that. We were happy with it on the last trip and never ran the Honda over maybe 1/2 throttle. You use to be able to buy a stock 8 pitch for the Honda, but I couldn't find one any more.

c ya,

Sum

 

[beamreach]

All I can speak from is experience. We recently set out late to reach an island 4 miles away before nightfall and find an anchor. Our Mac 26s is powered by a Tohatsu 8hp 4 stroke long shaft, not extra long, with a 3 blade prop with a pitch of 6.5. The wind was blowing 20 knots out of the southwest, gusting more. The island was due south. I never ran the motor wide open, probably 3/4 throttle most of the time. Seas were breaking over the bow sometimes depending on how I angled the bow into them. The prop never totally left the water but I could hear alternating revs from the engine. The motor got us there in plenty of time to find that anchorage. In my opinion, this is a very good motor for this boat. Had a mac 25 once with a 9.9 Johnson on it and I notice no difference in performance. Disclaimer: My 2 cents ain't worth nothing, but I do like this Tohatsu!

 

[Sumner]

.......... Our Mac 26s is powered by a Tohatsu 8hp 4 stroke long shaft, not extra long, with a 3 blade prop with a pitch of 6.5. ................. My 2 cents ain't worth nothing, but I do like this Tohatsu!

Do you have elect. start? If so where is the starter key/button?

Is the shift on the tiller handle or the side of the case? Hard to get to?

How about steering? Can you go lock to lock or close to it?

I like the Nissan 5 HP (made by Tohatsu) that we have and wouldn't mind a larger Nissan to pick up the elect. start.

How about you Yamaha guys? Do any of you have the 8/9 HP with elect. start and the power tilt and high thrust? I like the shift on the lever. Do you like yours? Would you buy another one?

Thanks,

Sum

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[beamreach]

Hey Sum,
The shift on my motor is on the side, not hard to get to. The electric start button is on the front of the motor, not the handle, not hard to get to. I can't go lock to lock and don't need to because I steer with the tiller and leave the motor tightenened in one position all the time. The thing that makes this work for me is a circle of stainless I bought from Cabelas that encircles my prop and protects my Ida rudder at all points of elevation from the prop.

 

[Sumner]

Hey Sum,
The shift on my motor is on the side, not hard to get to. The electric start button is on the front of the motor, not the handle, not hard to get to. I can't go lock to lock and don't need to because I steer with the tiller and leave the motor tightenened in one position all the time. The thing that makes this work for me is a circle of stainless I bought from Cabelas that encircles my prop and protects my Ida rudder at all points of elevation from the prop.

Thanks, the reason I asked is because we always anchor and I'm up on the bow with the anchor and Ruth runs the outboard and tiller and she is 5-2 and doesn't have the longest arms in the world. Right now she has quite a reach down for the shift lever on the Honda and forget restarting the motor if it dies.

I made a shift handle, but we only used it about 1/2 the time on the last trip. It has so much leverage that it is a little confusing feeling the shift postions, especially going back into neutral.

c ya,

Sum

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[Robspan]

The 9.8 Tohatsu has the shift on the front of the motor, which would make it easier to get to.

My wife has no interest in running the motor, or learning how, though she'll take the tiller or put the motor in neutral if I ask her to. When we anchor, I put out the anchor gear ahead of time and run the boat to the spot where I want to drop it, then go up to the bow, drop and set it. I may have to go to and from the bow 2 or 3 times before everything is the way I like it but it sure cuts down on the marital friction.

This discussion suggests one other advantage of the 6hp. The powerhead seems to be smaller, so if it's attached to the transom, you should be able to turn it more from left to right.

 

[Sumner]

........My wife has no interest in running the motor, or learning how, though she'll take the tiller or put the motor in neutral if I ask her to. When we anchor, I put out the anchor gear ahead of time and run the boat to the spot where I want to drop it, then go up to the bow, drop and set it. I may have to go to and from the bow 2 or 3 times before everything is the way I like it but it sure cuts down on the marital friction.................

On our last trip we were out about 24 nights and on a different ancorage almost every night on two lakes we had never seen before. The lakes were formed by glaciers and were very deep (one was over 400 feet deep in less than a 1/4 mile from shore) and the shores dropped off very quickly. This presented a problem in finding an anchorage where the water was shallow enough to throw the anchor and not have to let out more rode than we had and then the problem was if the shallow water was too close to shore we could swing into the shore on the rode.

We would hunt along likely looking spots running as parallel to the shore as possible with me on the bow looking and directing and Ruth on the tiller steering and watching the depth finder and calling out depths every 15 seconds or so. Also most of the time the water was so clear I could see the bottom once we were in 20 feet of water, but also because the water was so clear it was hard to tell how far down it really was. If we could find a place where the water was 9-12 feet deep and I felt we were at least 100-120 feet from shore I would toss the anchor. When Ruth would hear or see the anchor go in she would immediatelly turn the boat away from shore and put the motor in neutral and we would coast to a stop as I let the rode out to the mark..........

..............I wanted on the line. The markers I put on are sure better than the ones with the depth printed on them that take time to read or trying to remember the colors. These you can see as the line is running out of the rode bag real easy. One marker is at 25 feet, two at 50, three ar 75 and 4 at 100 and then they start over again. They indicate the lenght of line and to that I have to add the 30 feet of chain.

One thing we started doing was I quit yelling at Ruth where to go and use hand signals. I keep my right hand down low and and point to port or starboard or take my hand with the fingers straigh down and move my hand fore aft to stay on this course. It works great and we have become actually closer becoming a team while anchoring or using the same method docking or running in narrow channels. If you are around others the hand signals make it look like you know what you are doing vs. the yelling back and forth.

Now this all sounds great and wonderful, but it was developed after some major mistakes like running into rocks on the shore, hitting the center board on the bottom and kicking the rudder up.

Sorry to get off the topic of motors...........

Sum

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[walt]

A buddy of mine warns visitors on the the boat that words like "please" are probably not going to be used if things are about to get out of hand and he needs something to happen. Im pretty sure if I tried to get my wife to do something on the boat, Id get smacked in the head with the anchor (by her) so even when she is on the boat, its pretty much the same as being single handed. Working this way has somehow kept us married for 26 years now (or is that 27 or??).

In a post "a few back", Robspan talked about a fixed bracket off the transom which likely allows just about any under 10hp to fully rotate. This probably depends on the outboard but sounded like you could get by with just moving the outboard back by about 4 inches - might have to build a custom bracket to minimize the distance, Id probably do it out of Aluminum. I dont think 4 inches back would bother me too much.

I still wonder about an outboard with remote controls mounted in the transom well area. The remote control Nissan/Tohatsu/Mercury would probably have no problem rotating since no tiller assembly. Figuring out some sort of steering would be a lot less complicated that some of the other stuff Sumner has fabricated.. The drawback is that remote control seems to add about $800 or something like that to the outboard cost and probably ends up weighing more.

edit - my 4 hp Tohatsu will rotate just fine on the 26S transom. Unfortanetly its a short shaft so I can tuse it.. But I did test the rotation.

 

[Chris & Lenore]

I'm still wondering what "currents" have to do with any of this? The best you can do is hull speed through the water. If the current is moving faster than hull speed then you go backwards regardless of horsepower.

If a 6 hp can do hull speed in heavy winds then overall performance is going to be the same as with a 9.9 I have no idea of difference in fuel economy for these two scenarios. Would there be a substantial difference in purchase price?

Speaking to the question of Yamaha - I love our 9.9 extra long shaft high thrust. It is worse in weeds but great everywhere else. An as important for me - parts are easy to obtain and WAY LESS expensive than with my previous outboards.