Smallest motor on Zip?

Outboard designs up to 14'

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sproggy
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Smallest motor on Zip?

Post by sproggy » Mon Sep 17, 2018 7:39 am

I know people usually ask "what's the biggest motor I can fit to a.......?". Well this is the opposite. What's the smallest motor anyone's fitted to a Zip?

I spent some time wandering around boats last week and a 25hp Yamaha motor, which I was planning around, is physically pretty big. Given that I will rarely have the opportunity to run at anything more than 6mph a lump of metal that big hanging off the transom seems like overkill - it'll spend its time barely above idle. Say I was aiming for 10mph top end, I'm thinking something between 10 and 15hp would be plenty while saving a bunch of weight.

Does anyone have experience of running a small motor on a Zip or similar hull?

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BarnacleMike
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Re: Smallest motor on Zip?

Post by BarnacleMike » Mon Sep 17, 2018 8:39 am

I have wondered something similar... how small a motor would still be effective on the Zip. The new 4-stroke 25 hp motors are too big, imho... partially a result of being 3-cylinder designs. The Evinrude ETECs that size are thankfully 2 cylinder.

If I knew that my boat would almost always be used on the idle-speed-only lake I currently go to, I'd probably put a short shaft 15 or 20 HP on it. Most likely the 20 for me personally... "just in case."
-Michael

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sproggy
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Re: Smallest motor on Zip?

Post by sproggy » Mon Sep 17, 2018 8:58 am

How big do you go 'just in case'? :lol: I figure 10hp would easily be enough for 6mph but a 15hp would be working less hard.... I don't think many of the boat speed calculations are effective at such low powers/speeds for planing hulls.

I was originally going for a Yamaha F25 which is a twin (unusually for a 25) and therefore lighter than most of the 4-stroke competition but having stood next to one mounted on a boat on a trailer it's still a big old thing. I considered an ETEC too but, however efficient they are, I'd worry about running a 2-stroke at low revs all the time. And 25 is the smallest ETEC.

I could almost get by with twin Torqueedo Travel 1003s and make up the weight in the transom (they weight 14kg each) with some extra battery capacity.......

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Bill Edmundson
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Re: Smallest motor on Zip?

Post by Bill Edmundson » Mon Sep 17, 2018 10:44 am

I think 10hp would do it to get you to 10mph. A good electric trolling/fishing motor would get you to hull speed, 5.5 mph.

Bill
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vupilot
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Re: Smallest motor on Zip?

Post by vupilot » Mon Sep 17, 2018 11:30 am

I think these days a 25 is a great motor for a Zip using modern motors. But if you aren't worried about getting on plane and running fast a 10hp would be plenty for putting around like a pontoon boat

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sproggy
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Re: Smallest motor on Zip?

Post by sproggy » Mon Sep 17, 2018 11:51 am

Pretty much all inland waterways (rivers and lakes) in the UK are subject to a 4/5/6mph speed limit with the exception of a few small waterski lakes. The only place you can go faster is on the sea or estuaries and the Zip isn't built for speed on rough water. You might get the odd super-calm day on an estuary where you could run a 25 somewhere near flat out but if I got one of those a year I'd be very lucky. So optimising for a slower pace seems to be sensible. Really I'm building the wrong hull shape (should have chosen a displacement hull) but it's too late to change that!

Sounds as if a 10 or 15 would do the job - thanks for the feedback. I'm going to the Southampton boat show later in the week to look at both paints and motors. Slightly premature for both but it doesn't hurt to plan ahead.

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vupilot
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Re: Smallest motor on Zip?

Post by vupilot » Mon Sep 17, 2018 2:04 pm

Yeah, if your going on canals with speed limits then youll be plenty happy with 10-15hp. 15 might just get you on plane when your are light.

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