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Old 04 August 2012, 03:08   #11
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Country: UK - Scotland
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Thanks chewy and Smithyyy.
I know one engine will get me home as that is the engine I use as my main engine now.
I like the Honda 20s as they have a backup recoil if the elec starter should fail or battery die.
Anybody fancy hazarding a guess if 2 x20hp = about 30hp?
Thanks to all for the interest
Cheers
Danork
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Old 04 August 2012, 03:14   #12
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Thanks kubcat... With another 75/80 kg person the speed is reduced to just on the plane around 13 knots.
I know there are many disadvantages and if I buy a brand new honda and the setup is total **** I am going to be very unhappy!
If I could try it out and then change my mind if it didnt go very well that would be great... But thats not how it works!
Thanks for the input
Cheers
Danork
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Old 04 August 2012, 04:22   #13
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I've had a starter motor fail on me before - but luckily I was still in the harbour, but that's what auxilliary engines are for. Because you're in Orkney there's a real chance you could be out and not see another boat, depending on the season. Look at the main engine and decide if you want the Honda 50hp, then look at an auxilliary back up as a suitable option, rather than a twin set up. For example a Tohatsu 5hp 2 stroke weighs 19kg, is relatively slim, and has its own integral tank, and can be connected to an auxilliary tank (with pre-mix).
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Old 04 August 2012, 08:29   #14
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Thanks spartacus. All very helpful.
What ever choice I make, there will be a weight consideration. I know with another 75kg person aboard my speed drops considerably. If I get a bigger engine say 100kg and auxiliary, that will be about 120kg.
If I go for 2 20s twill be about the same. I don't need 2 batteries as they can be hand started. Which ever way I will be adding about 60kgs which is about the weight of the extra person. How much performance increase will I notice with 60kg extra aboard all the time?
I was looking at the traditional mariner 30 2 stroke (only for commercial new). weighs in at 51kg! Wow. Thats lighter than the 20 honda!
So many decisions!
cheers
Dan
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Old 04 August 2012, 09:10   #15
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Quote:
Originally Posted by Smithyyy View Post

Clearly you burn more fuel with twins, on the other hand when you're not in a hurry you can poddle around on one and probably burn less than a larger single would
This isnt really the case. Sure, two 20s will burn more than a single 20, but the OP replaced a 50. As such, the fuel burn of twin 20s will likely be close to the burn of the single 50.
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Old 04 August 2012, 10:17   #16
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Originally Posted by Geoellis View Post
This isnt really the case. Sure, two 20s will burn more than a single 20, but the OP replaced a 50. As such, the fuel burn of twin 20s will likely be close to the burn of the single 50.
Twin 20's will never be as quick as a single 50 and I think the fuel consumption will be close.
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Old 04 August 2012, 12:58   #17
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Thanks chewy.
I'm guessing equal to about 30hp?
If I could guaranty a gain in speed of say to 25 knots (from 19) ie 6 knots more, I would probably go for it.
I can get one shipped up here fairly painlessly.
Also, an unrelated question, how do I paste in a photo? Want to show my landrover rig towing my boat the vast distance to the slipway (less than a mile!)
Cheers
danork
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Old 04 August 2012, 13:31   #18
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First of all, you're 10 hp less. Next, the drag of more running gear will slow the speed down. Finally, there's the weight consideration. Im not sure what this all translates into regarding speed loss numbers, but for a small boat there really is no rationale for twins over a single
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Old 04 August 2012, 14:01   #19
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Hi

I am reading this with great interest and thanks for the kind words but thought I should just add one more consideration for the debate.

if it is 20 x 2 then we dont have a counter rotation engine option.

Dave

ps Danork, your maths are about right re 2 x 20hp = around an extra 10 hp in real terms but and here is the nasty rub. I would prefer 1 x 50hp chugging along than 2 x 20 hp at full tilt as the 20's will burn more fuel and you will be running them far harder than the 50hp.

oh and we still have the counter rotation problem.

PPS There is a nice searider 4.7 going cheap. The members on here can tell you more about these than me so again back of to them and i will read with interest.
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Old 04 August 2012, 17:42   #20
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Have you got the space to double up the control boxes and thought how your going to get the steering cable to fit without it sticking out further than the beam of the tubes or are you going to use a baystar kit? More to this than bolting another engine on.
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