70 hp engine om a zip ????

Designs for inboard or outboard power

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Bram
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70 hp engine om a zip ????

Post by Bram » Fri Sep 06, 2013 12:55 pm

Is it possible to put a 70 HP outboard engine on a zip if you reinforce the transom ????

gdcarpenter
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Re: 70 hp engine om a zip ????

Post by gdcarpenter » Fri Sep 06, 2013 1:40 pm

Yes, most anything is possible. It is my understanding that with a full height transom a ZIP 'would' be rated for a max. 40 HP by the Coast Guard, or whoever rates those things.

That being said there are ZIPs with 40, and I believe up to 50 HP.

There is one ZIP that was 'stretched' 3' or 4' in length that has run an 70 or 80 HP, you should've able to find that build using the search feature here.

Personally, I feel that using a very solidly constructed motor well to add extra strength to the transom, as well as other reinforcements, it could be done - others I'm sure will think differently. Should I ever restore the 1961 Mark 700 (InLine 6 cyl. 70 HP - Tower Of Power) sitting in my basement, I would seriously consider bolting it to my ZIP.

As to whether or not the handling characteristics of the ZIP are up to the challenge of 70 HP, I leave that to those far more knowledgeable than me.
This is my first, last and only boat build.

http://www.gdzipbuild.blogspot.com

matt167
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Re: 70 hp engine om a zip ????

Post by matt167 » Fri Sep 06, 2013 8:41 pm

With a 20" transom, I would say most likely it would take it. The boat would rate nowdays for about 40HP prop shaft/ BIA rating.. When the old motors were re-rated when they went to prop shaft ratings in the 80's, they typically dropped 5-10hp, ex: the old 44CI Merc 500 was sold as a Mariner 40hp right near the end of it's production... So with this, you can assume your boat could take a more modern 50hp and it will operate like an old 60hp, or a re-rated motor like an Evinrude/ Johnson 3cyl 55hp. That engine was actually tuned and re rated to 70hp a couple years after it's introduction ( same weight, same motor tho ). They took that motor and gave it a few more cubes in 1987 when the rating switched to prop ratings so that it was a true 70hp, tho still basically the same... I would say that the Johnnyrude 70hp would be your 'hot ticket' 70hp, and they built millions of those things all the way to 2001 when OMC went out. They are not hard to find

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Roberta
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Re: 70 hp engine om a zip ????

Post by Roberta » Sat Sep 07, 2013 7:21 am

I think the Zip could handle a 70 hp motor of the older short shaft style with a properly reinforced transom, but why? The boat is not designed to be a race boat. Newer 4 stroke motors above 40 hp are way to heavy for this boat. If you want speed, build a boat designed for that. If you want classic styling, build the Zip.

Roberta
Roberta "Queen of the Boat Builders"
Built Zip "Oliver IV", Super Spartan "Jimmy 70", and Torpedo "The Glen L".

Moeregaard
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Re: 70 hp engine om a zip ????

Post by Moeregaard » Sat Sep 07, 2013 12:58 pm

I'm with Roberta on this one. I think the Zip could handle the 70 horses, but I also think that the boat could become a real handful with too much power. The Zip is a really nice boat when powered as designed, but I wouldn't want to see one at much more than 40--45 MPH, unless the water was really, really flat and protected. Better off to put those 70 ponies to work on a Malahini or a Rebel. Just my two cents...

-Mark Shipley
A boat is just a wooden box with no right angles.

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travis24
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Re: 70 hp engine om a zip ????

Post by travis24 » Sat Sep 07, 2013 5:35 pm

Ask John he has an 850 Zip for Sale.

http://milwaukee.craigslist.org/boa/4030948294.html.
It's like anything you Build. You have to be Patient.

Measure Twice, cut Once.

Keep em Alive ! Vintage & Antique outboards

https://waterhogsworks.com/

Bram
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Re: 70 hp engine om a zip ????

Post by Bram » Wed Sep 11, 2013 2:30 am

Well a got the building guide for the zip and there's a little map in it were they discribe how the transom can be reinforced for an engine up to 85 HP.

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jprice
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Re: 70 hp engine om a zip ????

Post by jprice » Wed Sep 11, 2013 12:16 pm

Is this the doc you're referring to? http://www.glen-l.com/weblettr/weblette ... rwell.html

I got the same thing with my build, but I think that's a generic transom doc. It's not implying that those powers could be used on any model.

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Gayle Brantuk
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Re: 70 hp engine om a zip ????

Post by Gayle Brantuk » Wed Sep 11, 2013 1:42 pm

Yes, the transom specs are general and not specific to the Zip. 70 hp is over powered in our opinion for the Zip.

Brian Eager
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Re: 70 hp engine om a zip ????

Post by Brian Eager » Wed Sep 11, 2013 7:12 pm

Here's a link that may be handy:

http://files.dnr.state.mn.us/education_ ... ilders.pdf

The important thing to remember is that if you turn the helm hard over and have an excess amount of power on, there is the chance of capsizing. Could spoil your whole day. That's why there are guidelines for power, especially in outboards.
Noah was a first-time boatbuilder

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jprice
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Re: 70 hp engine om a zip ????

Post by jprice » Thu Sep 12, 2013 6:45 am

That's an interesting doc. But not sure I trust it.
According to that formula, my 16' celerity would be rated for 135HP! :shock:

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