Outboard size for MFG 19? - Page 2 - SailNet Community
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post #11 of 16 Old 07-29-2008
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A Mac 25 is a much bigger boat. A 7.5 HP or 8 HP four stroke is an awful lot of weight to be hanging off the transom of a 19' sailboat.
Funny you should say that Dawg.. our little Hartley has a Johnson 7.5 that has been with the boat since the early 80's. Better not say that too loud - it might get upset!!

There is an article in the latest edition of Australian Sailing on this very topic and a few of us have had exactly this discussion to work out the smallest permissible outboard for the TS18 Class. The guidelines we were working to (from the Racing Rules) talk, not just about hull speed, but about maintaining hull speed into a 12kt breeze for 3 hours.

The end result was that, for an 18-20' boat, even though you could probably get to hull speed with a 2hp going flat-out, the smallest outboard you should have is a modern 3.5hp or old 4hp with around 15 litres (whatever that is in your currency) in fuel.

Remember: Outboards work best at 3/4-full throttle, so getting a big one is not necessarily better.

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post #12 of 16 Old 07-29-2008
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Yes, but I bet your 7.5 Johnson is a two-stroke, not a much heavier four-stroke, which is likely to be all the OP can buy nowadays.

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Originally Posted by Hartley18 View Post
Funny you should say that Dawg.. our little Hartley has a Johnson 7.5 that has been with the boat since the early 80's. Better not say that too loud - it might get upset!!

There is an article in the latest edition of Australian Sailing on this very topic and a few of us have had exactly this discussion to work out the smallest permissible outboard for the TS18 Class. The guidelines we were working to (from the Racing Rules) talk, not just about hull speed, but about maintaining hull speed into a 12kt breeze for 3 hours.

The end result was that, for an 18-20' boat, even though you could probably get to hull speed with a 2hp going flat-out, the smallest outboard you should have is a modern 3.5hp or old 4hp with around 15 litres (whatever that is in your currency) in fuel.

Remember: Outboards work best at 3/4-full throttle, so getting a big one is not necessarily better.

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post #13 of 16 Old 07-29-2008
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Yes, but I bet your 7.5 Johnson is a two-stroke, not a much heavier four-stroke, which is likely to be all the OP can buy nowadays.
Yep, you're right on both counts

(Note to self: The Dog Is Always Right)

FWIW: Recommended four-stroke outboard size for Hartley TS18 = 4hp; Hartley TS21 = 6hp - although many use an 8 or 10..

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post #14 of 16 Old 07-30-2008
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The main factor I've found in choosing an outboard is its weight. For security reasons I have to lift the o/b off the transome, of my 20ft loa Sea Wych, and store it in the cabin! This can be quite an interesting operation/spectacle!....in the choppy Thames estuary off Britain's east coast. Hitherto, I had a Seagull Kingfisher 6hp 2 stroke (long shaft) for say 3 hours continuous motoring against a foul tide. I'm considering now, as earlier posts suggest, buying a 4 stroke 6hp for reliability, but what is the weight premium over an equivalent lighter 2 stroke? Also max (4 stroke) full fuel tank duration?
Cheers BS London UK
http:journals.aol.co.uk/spcdesign/BargainIssue
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post #15 of 16 Old 07-05-2015
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Re: Outboard size for MFG 19?

I used to own an MFG 19 for 8 years and tried a 4hp Merc, it felt ok if you are on a small sheltered lake with no waves and limited winds. I stayed with the 6hp Johnson as it was far more suited power-wise to the boat especially if you have any more than one person on the boat. Being on Lake Ontario we often had some waves and wind to deal with. I only had the short shaft which I would not recommend on a larger lake where you may experience waves of any significant size. As previously mentioned definitely go for a long shaft. If you plan on putting more than two people with gear an 8hp long shaft would be very nice to have but it can get more costly to initially purchase. As for fuel consumption the 6hp johnson was better then the 4hp Merc. I did quite a bit of trolling around on the motor and a 30L tank was way more than you would need for typical use in one season. I ended up with 10-15L of fuel at the end of each season which I would then use in my lawnmower/snowblower.
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post #16 of 16 Old 07-06-2015
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Re: Outboard size for MFG 19?

Quote:
Originally Posted by michaelkaczmarek View Post
I used to own an MFG 19 for 8 years and tried a 4hp Merc, it felt ok if you are on a small sheltered lake with no waves and limited winds.
This is a 7 year old thread and the original poster hasn't posted since then.

Catalina 34

Last edited by chuck53; 07-06-2015 at 11:07 AM.
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