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New 115 hp mercury CM four stroke

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    Posted: 13 Jun 2018 at 9:10pm
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Ok if you start reading between posts on buy sell on these motors you'll understand why I want to know.. Let me know what you know and what you think powering a 6 mtr glass boat. Relatively heavy deep vee from what I know of them. Mate has the larger hard top (awesome boat ... mako) and I have seen this model the 595 challenger at a boat show few years ago. Steps I'd really appreciate your opinion on this one. Do the numbers.
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Post Options Post Options   Likes (0) Likes(0)   Quote Steps Quote  Post ReplyReply Direct Link To This Post Posted: 14 Jun 2018 at 10:12am
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It comes down to the total weight on the water.
 Gear , fuel ppl everything.
To perform well in chop/ seas requires good reserve power at that rpm and speed...the ability to set the throttle and just steer. This for plaining hulls around 6m down to just under 5m a WoT speed around 42mph to just under 50mph. Above that you are over powered.
 Over powered gives even more economy, faster cruise and little better chop performance... just got to watch throwing nppl over he stern on a normal take off.
The area the boat sits on at normal cruise (approx midway or just behind mid way and stern) is the area of friction. most plaining hulls are very similar in area here.
Ball park...
 5.5m 1200kg (total weight) well powered 140hp 46 mph min 115hp 42 mph
6m 1900kg (total weight) well powered 200hp 43mph min 185hp 40 mph.
To do so outboards must be set at correct height at cruise speeds and prop with correct slip numbers at WoT and at normal cruise speed around 3800/4000 rpms.. 
 Ideally pitched WoT fully loaded mid or just below mid manufactures max rpm range (@correct slip %)

 Note in spite of general misconception, pitch will not make any significant change to WoT speed if in manufacture rpm range... its the hp available in that rpm range that over comes the friction to move that weight that determines max speed... but will effect your cruise speed and rpm numbers.. ince hp varies to to engine rpms.

 PS is this posted in the right section?.


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Post Options Post Options   Likes (0) Likes(0)   Quote shaneg Quote  Post ReplyReply Direct Link To This Post Posted: 14 Jun 2018 at 7:12pm
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Thanks Steps for your reply.
Sorry posted in wrong section.
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Post Options Post Options   Likes (0) Likes(0)   Quote krow Quote  Post ReplyReply Direct Link To This Post Posted: 14 Jun 2018 at 8:29pm
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I have one Shane. 6m Ramco. This model is highly recommended by the service crew at Warren Hay (no turbo). When I brought mine second hand from Aucks April 2017 they had had no issues with them to date. I've clocked up a couple of hundred hours and no issues apart from user error and running it out of gas a few times on the tot before plugging in the underfloor (Just 100ltr and I do big days sometimes). When you do that it goes into alarm mode and thinks the fuel pump has shat itself. Found out I had to turn it off to clear the alarm. Noisy for a 4/ on the plane. Good economy. Game fishing I've been almost spot on Nautical Miles to Litres. I don't even need their smart gauges to tell me how much fuel I've used it's so close. 
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Post Options Post Options   Likes (0) Likes(0)   Quote shaneg Quote  Post ReplyReply Direct Link To This Post Posted: 14 Jun 2018 at 9:10pm
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Thanks Doug , yes they sound like a very good motor from what else I have read. Your certainly going to test it hence a good recommendation.
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Post Options Post Options   Likes (0) Likes(0)   Quote Catchelot Quote  Post ReplyReply Direct Link To This Post Posted: 14 Jun 2018 at 10:36pm
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Originally posted by shaneg shaneg wrote:

Thanks Doug , yes they sound like a very good motor from what else I have read. Your certainly going to test it hence a good recommendation.

When do we get a pic of this new big Merc on your Jetski Shane? LOLClown
"The sea, once it casts its spell, holds one in its net of wonder forever." - Jacques Cousteau
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Post Options Post Options   Likes (0) Likes(0)   Quote Tzer Quote  Post ReplyReply Direct Link To This Post Posted: 19 Jun 2018 at 5:34pm
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Originally posted by shaneg shaneg wrote:

Ok if you start reading between posts on buy sell on these motors you'll understand why I want to know.. Let me know what you know and what you think powering a 6 mtr glass boat. Relatively heavy deep vee from what I know of them. Mate has the larger hard top (awesome boat ... mako) and I have seen this model the 595 challenger at a boat show few years ago. Steps I'd really appreciate your opinion on this one. Do the numbers.


Have a look here, hyperlink not working



www.tzercharters.co.nz
https://www.facebook.com/pages/Tzer-Charters/254559404707318
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