Outboards - too much power?

[Rightsideup]

Ladies and gents,
Quick question re the max hp rating for my newly bought 19ft Daysailer...think it's a 73, and have the chance to buy a 10hp 4stroke Honda long shaft ... is this too much power? too heavy? We are on a Lake that gets up pretty quick but don't want too much weight. Is this too much motor?
Thanks in advance,
Newsailer

 

[kloudie1]

I used to use a Honda 7.5hp on a 23 foot cabin boat.. That was plenty motor.. My opinion is that a 10 is too heavy and something like a 5 (long shaft) is plenty for a 19 foot boat and not as heavy.. The 10 weighs around 98 pounds, the 5 weighs 60 pounds.. A Tohatsu/Nissan 6 weighs 57 pounds.. 40% less than the 10.
It is not the extra power that is a problem, it is all that extra weight on the back..
Have Fun !!

 

[Ted]

Outboards- too much power

I have to agree with Kloudie1. A Honda 10 is a pretty substantial hunk of hardware. I had a Honda 7.5 on a 25 foot 3750 pound displacement sailboat and it was perfectly capable of powering us through the worst conditions. (as long as the prop stayed in the water) A used two stroke would be a better choice if you're allowed to use it in your lake. They are much lighter than four stroke motors and tend to last forever.

 

[Prime Time]

Too Big

Hi,
I have a similar boat, a Flying Scot. I have used a 3.5 HP outboard and that was plenty to move the boat at about 5 knots with 3 people aboard.

The disadvantage of the larger engine is that it is very heavy.

 

[Ray Bowles]

The Honda 10 hp and the Honda 7.5 hp are the same engine, just different camshafts. Weight is the same on both.
Both are more motor than needed and too heavy. A 2.5 to 5 hp would be great. 2 cycle engines are lighter but get poorer milage and smoke. The time when you use an engine is when the wind doesn't blow and that's when the fumes follow you. I'd go 4 cycle if possible.
I have owned and extensively sailed boats both somewhat larger and somewhat smaller so I feel good with that advise.
Enjoy your boat. Ray

 

[Ed Schenck]

I have the Flying Scot's father, a 20-foot Highlander and about 500 pounds. I have used two motors, a 1 hp and a 2 hp. Strictly for getting back into the slip between all the pontoon boats. But I have motored four or five miles with both engines. The 1hp only weighs twelve pounds by the way. Air-cooled and has a neutral. Neat engine.

If you are venturing way out in a big lake that can kick up quickly then a 2.5 or 3.5 would be warranted I think. Definitely not more than 5hp.

 

[tommays]

This outboard stuff kills me every time it comes up as its clear most owners have never invested in the correct high thrust prop to allow the motor to make its rated HP

I dropped the 105 dollars on the prop and rescued Seafever at 29' and 8000# with a 4 HP motor which moved the boat at 4.5 knots with a really dirty bottom from NYC out the sound over 16 miles to a yard and i only had to run it at about 3/4

The same motor on my J24 will push the boat through 35+ knot winds with out issue

 

[txjim]

A more important question: Will a 10hp motor rip the motor mount off of your boat? Even if you never go full throttle, you will likely do damage. Have you looked at the manufacturer's recommendations?

 

[Ross]

The question of weight aside it makes no difference what the horsepower rating of your engine may be. The ability of the propeller to convert that horsepower rating into work is where you get the thrust.
I turn a 13x13 three blade prop on my Islander with a ten HP diesel. There is a cabin cruiser on our dock that runs the same size prop on a big V-8 engine and gets nearly 40 MPH. The difference is the speed the prop turns. Mine never gets over 1000 rpm and his idles at close to that and tops out at about 5000rpm.
I am talking shaft rpm not engine.

 

[RichH]

This outboard stuff kills me every time it comes up as its clear most owners have never invested in the correct high thrust prop to allow the motor to make its rated HP

Bingo!!! absolutely and totally correct.
On my 20ft. 650lb. sportboat I can get it up on a plane with a 3HP ... but it took some bodacious prop pitch changing to do this, and so that the OB didnt go beyond 'max. rpm'.

If you want very short OB life, let the OB 'lug' at relatively low rpm and high throttle. You really have to let them 'spin' so that they develop full HP.

3-4 HP should be more than adequate for a lightweight DS. 10 HP is gross 'overkill' and you'll never 'spin' the engine at its designed 'cruise rpm'. Youll probably be able to pull a waterskier with a 10HP on a DS.

 

[Prime Time]

As an aside, I have a 9.9 4 stroke on an Achilles RIB. It goes so fast that it is scary! I'd probably trade it for a near new 3.5 or 5 hp 4 stroke.

 

[Ross]

As an aside, I have a 9.9 4 stroke on an Achilles RIB. It goes so fast that it is scary! I'd probably trade it for a near new 3.5 or 5 hp 4 stroke.

You don't have to open the throttle wide. I have an '87 Volvo with a turbo that can be scary fast but I don't drive it that way.

 

[Rightsideup]

Thanks to all

Many thanks to all, I am also on the track of a 5hp two stroke, so that is the way to go. We are looking forward to getting out there next season (upgrading from a trolling motor assisted 16ft canoe) so should be fun!
regards to all.RSU

 

[Rightsideup]

Found a 5

Found a 5hp 4s Honda...will the DS need a long shaft? RSU

 

[chuckwayne]

Re: Found a 5

If it's an O'day Daysailer she's only 16'9" and the standard OB is 3hp. Usually, you need a long shaft to get the outboard head above the transom. I wouldn't go above a 4hp, preferably a 2 stroke because the 4 strokes are a lot heavier.
Chuck Wayne
DS 13031

 

[Prime Time]

???

You don't have to open the throttle wide. I have an '87 Volvo with a turbo that can be scary fast but I don't drive it that way.

Ross, my point was that the motor has far too much power than is needed. For some reason if you wanted to go all out, the handling of the boat feels tenuous. Despite this, the boat is rated for up to 15 hp.

 

[Rightsideup]

is 19in too short?

Ladies and gents...i have been told by vendor that the 5hp is 19in from the bottom of the motor to the top of the (cavitation?) plate..this would be a short shaft and too short?? The previous owner said he used a short shaft 7.5...but he was a bit of a balloon. The 2s 5hp long shaft I was after has gone. Should I forget about the 5hp4s Honda motor?? The vendor advises that the motor is 28in top to bottom...so it must be a short shaft and is a good price.

 

[Ross]

Re: is 19in too short?

I think that you need better detail. The dimension you are concerned with is from the top of the motor mount on your boat down to the water and however much more you want for the propeller.

 

[Rightsideup]

thanks

Thanks Ross - the transom seems to be very shallow, from what little knowledge I have...maybe 15in, and our lake is weedy...but I guess the short shaft is too short.RSU

 

[LANCE ON CLOUD NINE]

I have a 5 horse Tohatsu, and it is plenty for my O'Day 23. It is smooth and quiet. If I had your boat, I would get a 3.5 http://www.onlineoutboards.com/Tohatsu-3-5-hp-MFS3-5BL.html Good luck- have fun!