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Catalina/Capri 25/250 Sailor's Forums

Catalina 25 Specific Forum

Honda 9.9 vs 15 hp

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johnpurvis
Deckhand

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USA
2 Posts

Initially Posted - 09/30/2013 : 16:37:29

Recently returning from a trip to Lake Powell my '06 WB C-250 was rear ended. The motor was smashed and needs to be replaced. The estimate for the repair is close to that of a new motor. My question: does anyone have actual (mph) differences between the two motors. Next year I am planning to go to the San Juan s where the currents can be very strong. At Lake Powell the most consistent speed motoring was 6 mph while towing a dinghy. Will the 15 give me a speed advantage or just the same speed at a lower RPM? I appreciate any input on the subject.

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Dave5041
Former Mainsheet Editor

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USA
3758 Posts

Response Posted - 09/30/2013 : 17:02:01

Hull speed is the approximate limit of the hull through the water or water flowing past the hull. 15hp will give you better speed towing, but you are already near hull speed while towing with the 9.9. 15hp might help with chop or a lot of wind, but 9.9 is more than enough to get to hull speed in most conditions, and fighting current is the same as trying to push the hull above hull speed in still water. The stern just squats in the water as you increase throttle above hull speed as the boat attempts to climb the bow wave. Planing power boats have enough hp to climb over the bow wave.

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johnpurvis
Deckhand

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USA
2 Posts

Response Posted - 09/30/2013 : 19:22:33

Thank you Dave, this was very helpful. I guess I'll continue with the 9.9.

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Stinkpotter
Master Marine Consultant

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Djibouti
9080 Posts

Response Posted - 09/30/2013 : 19:37:50

I had (and Voyager Bruce has) the current Honda 8 model that is the same engine as the 9.9 (except that it's cammed for lower high-RPM HP and higher low-end torque.) It was all I needed in some very nasty conditions. As the other Dave says, your hull speed limits your top speed through the water, whether the water is moving or not. You can't make forward progress through a 6.3 knot current with any engine unless it's big enough to lift your bow out over the bow wave (semi-displacement mode), which probably needs 50+ hp.

Also, the current Honda 15 is the same engine as the 20--it's a pretty big hunk. (The 8-9.9 is no lightweight, but it's lighter.)

A Honda rep I talked to at a show recommended the 8 over the 9.9 for a heavy displacement hull like the C-25, because it is tuned for torque over HP.

Edited by - Stinkpotter on 09/30/2013 19:48:20

ftworthsailor
Captain

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USA
279 Posts

Response Posted - 10/01/2013 : 08:40:34

I was having problems with my 8hp Evinrude so purchased a used Mercury 6 hp Four stroke OB. It definitely has the power to push my C-25 around at hull speed. Very strong outboard.....

Edited by - ftworthsailor on 10/01/2013 08:41:05

awetmore
Master Marine Consultant

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USA
1144 Posts

Response Posted - 10/01/2013 : 11:17:19

The currents in the San Juans are something that you plan around, not motor through. It adds a dimension of fun and challenge to cruising in that area.

They are also nothing compared to further north in the Discovery Islands. One day in July this year we passed through 6 tidal passes and had to plan our arrival at each of them to avoid bad currents.

It's a lot of fun when you are use the currents to your advantage and get a boat with a 6 knot hull speed moving at 11 knots with no surfing involved.

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Dave5041
Former Mainsheet Editor

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USA
3758 Posts

Response Posted - 10/02/2013 : 08:20:53

Ahh, the Northwest. I passed on an opportunity on the Washington coast from June - August 2 years ago. I don't like having to show up for work every day for that long, but I might reconsider if the option comes around again.

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Stinkpotter
Master Marine Consultant

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Djibouti
9080 Posts

Response Posted - 10/02/2013 : 11:01:32

Where I'd be leery about 6hp is against strong winds and big chop. Absent those, it's probably adequate power since my 8 only took about 2/3 throttle to cruise at 5.5 knots. (Faster, IMHO, was a waste of fuel and noise.) Also, compared to the older 8hp Honda I had, the Honda high-thrust 8 could stop my C-25 as if I'd run into a pillow.

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Voyager
Master Marine Consultant

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USA
5369 Posts

Response Posted - 10/02/2013 : 16:33:04

I've been in a lot of rough current and nasty chop (current vs wind) and the Honda 8 is no lightweight. Even if you're not running at 5 kts over ground, I've never found myself in a situation where opposing current AND winds have ever stopped the boat. Slower - yes - but always made headway.
Of course in a 6+ kt opposing current, that's when we retire to the bar and wait out the tide!

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dlucier
Master Marine Consultant

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Virgin Islands (United Kingdom)
7583 Posts

Response Posted - 10/02/2013 : 16:49:25

The 15hp Honda develops it's max rated horsepower at 5,000 RPM, nearing the top end of its operating range. Unless you're pulling another boat off a shoal, you'll probably never operate your outboard at wide open throttle, meaning, you will never get up to the RPM range to use all 15hp. If you never go wide open throttle, seems like a lot of unused and wasted horsepower.

If you had the 10hp outboard and ran it at half throttle under normal conditions to get to hull speed, you would still have the entire other half of the RPM range in reserve, which again, you'll still rarely use or even need. I have an 8hp, and I can't remember going wide open throttle and I've been in stiff currents, steep waves, nasty chop, etc in the nearly twenty years I've sailed Lake Erie.

Edited by - dlucier on 10/02/2013 17:00:08

sethp001
Mainsheet C-25 Tech Editor

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814 Posts

Response Posted - 10/02/2013 : 17:18:03

My boat came with a 15hp Johnson. Dave B. already answered this really well, but I thought I'd add that my personal experience is exactly what he describes. So we never run the motor anywhere near full throttle.

Another advantage to a lower horsepower motor is some jurisdictions require boater training, but not if your boat's motor is below a certain hp threshold. A new law in Virginia requires anyone operating a boat with a motor over 10hp (even sailboats) to have completed a state-approved boater safety course. I would not have had to take it if I had the smaller motor.

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Stinkpotter
Master Marine Consultant

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Djibouti
9080 Posts

Response Posted - 10/02/2013 : 18:26:22

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by dlucier
 ...and I've been in stiff currents... in the nearly twenty years I've sailed Lake Erie.<hr height="1" noshade id="quote"></blockquote id="quote">

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by sethp001 ...A new law in Virginia requires anyone operating a boat with a motor over 10hp (even sailboats) to have completed a state-approved boater safety course....<hr height="1" noshade id="quote"></blockquote id="quote">I'll only say that I'm a fervent supporter of required boater safety courses and certification. Too many people think it's like buying a car and not having to get a license... I say it's too similar (asking for chaos), except that the water wants to kill you and your passengers.

Edited by - Stinkpotter on 10/02/2013 18:28:39

dlucier
Master Marine Consultant

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Virgin Islands (United Kingdom)
7583 Posts

Response Posted - 10/02/2013 : 18:51:36

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Stinkpotter
 <blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by dlucier
 ...and I've been in stiff currents... in the nearly twenty years I've sailed Lake Erie.<hr height="1" noshade id="quote"></blockquote id="quote">

<hr height="1" noshade id="quote"></blockquote id="quote">

Dave,

My marina is actually at the mouth of the Detroit river and I have sailed/motored up the Detroit River, across Lake St Clair, up the St Clair River, and to Lake Huron. Although the definition of stiff might be a relative term, there were times when my SOG was barely over a knot. As to Lake Erie, I've been caught out in some stuff where my speed through the water was decent, yet I was going backwards.

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Stinkpotter
Master Marine Consultant

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Djibouti
9080 Posts

Response Posted - 10/02/2013 : 19:39:45

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by dlucier
 Dave,

My marina is actually at the mouth of the Detroit river and I have sailed/motored up the Detroit River, across Lake St Clair, up the St Clair River, and to Lake Huron. Although the definition of stiff might be a relative term, there were times when my SOG was barely over a knot. As to Lake Erie, I've been caught out in some stuff where my speed through the water was decent, yet I was going backwards.<hr height="1" noshade id="quote"></blockquote id="quote">I know about the Detroit River--I used to live outside of Detroit. Lake Erie surprises me--today, the max currents were below .6 kts, and that only in a few areas, as shown [url="http://tidesandcurrents.noaa.gov/ofs/leofs/now_cur.shtml"]here[/url]. But I also know about seiches caused by weather systems, which I presume will cause more substantial currents to move the water from one end to the other. (...and I remember the pictures of your marina!)

In my area, if you don't watch the currents, they'll carry you into a buoy or onto some rocks before you know what's happening!

Edited by - Stinkpotter on 10/02/2013 19:46:28

Dave5041
Former Mainsheet Editor

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USA
3758 Posts

Response Posted - 10/02/2013 : 20:55:59

Yepper, I've sailed (and some motoring) from Port Clinton to Lake Huron a few times - the river can have some serious currents in some places

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dlucier
Master Marine Consultant

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Virgin Islands (United Kingdom)
7583 Posts

Response Posted - 10/03/2013 : 03:52:11

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Stinkpotter
 In my area, if you don't watch the currents, they'll carry you into a buoy or onto some rocks before you know what's happening!<hr height="1" noshade id="quote"></blockquote id="quote">

Yep. I've had my share of close calls due to currents with the freighter channel buoys, which are just minutes outside of my marina. It doesn't take long to learn to give them a wide berth on the upriver side, but I normally pass them on the downriver side, especially with an opposing wind that at times really churns up the water over the deeper shipping channel.

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