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my smartwave 4200 build

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Post Options Post Options   Likes (0) Likes(0)   Quote OuttaHere Quote  Post ReplyReply Direct Link To This Post Posted: 09 Apr 2021 at 1:00pm
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Originally posted by Steps Steps wrote:

600kg plus battery , cables, sounders, fish bins... so 650 seems to be pretty good ball park?



Actually their website says 297kg hull weight so who knows?
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Post Options Post Options   Likes (3) Likes(3)   Quote spin king Quote  Post ReplyReply Direct Link To This Post Posted: 17 Apr 2021 at 1:41pm
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weighed it today 20l of gas, fishing gear, life jackets and no ice beers etc... 750kg bang on!
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Post Options Post Options   Likes (0) Likes(0)   Quote OneWayTraffic Quote  Post ReplyReply Direct Link To This Post Posted: 17 Apr 2021 at 9:06pm
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Allowing 250kg for the trailer, that's about 500kg for boat and motor.
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Post Options Post Options   Likes (0) Likes(0)   Quote spin king Quote  Post ReplyReply Direct Link To This Post Posted: 18 Apr 2021 at 7:44am
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Originally posted by OneWayTraffic OneWayTraffic wrote:

Allowing 250kg for the trailer, that's about 500kg for boat and motor.


yep hull is 297kg motor is 113kg battery is 10.3kg fishing gear etc is 25kg fuel is 20l so 20 kg.
plus 80kg solo puts it at 545.3kg
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Post Options Post Options   Likes (0) Likes(0)   Quote Steps Quote  Post ReplyReply Direct Link To This Post Posted: 19 Apr 2021 at 10:05am
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So all up when did the test WoT how far off is the 650kg total gross weight on the water out by do u recon?
Can then enter accurate hull co efficient data into the data base.
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Post Options Post Options   Likes (0) Likes(0)   Quote spin king Quote  Post ReplyReply Direct Link To This Post Posted: 19 Apr 2021 at 10:22am
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Originally posted by Steps Steps wrote:

So all up when did the test WoT how far off is the 650kg total gross weight on the water out by do u recon?
Can then enter accurate hull co efficient data into the data base.

100kg out, total on water weight was 545.3kg
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Post Options Post Options   Likes (0) Likes(0)   Quote Steps Quote  Post ReplyReply Direct Link To This Post Posted: 20 Apr 2021 at 10:56am
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Cool.. Im happy with that...
The hull has little higher drag co efficient than I expected.. around 15 points lower (48 if dont re calculate for the slip below)

 And throw in that you have rather a high slip @ WoT 14%..
Ideally would be around the 5% which would give you another 3.5 mph WoT.

The corrected increase in slip would give you a 4000 rpms cruise around the 23/24 mph.

When you say "....fully trimmed up..."
Do you mean the engine is fully trimmed up. \or fully trimmed up for THAT speed...just before ventilation/ bow porpoising?
 If over trimmed  (fully up) that will cause excessive slip.
  Ideally The motor should be mounted at an angle so one can over trim @ WoT a little.
 Mine I ventilate just below 1/2 trim.. if was to the book It would not be quite so sensitive at the ventilation point..
 In saying that it is a general use boat not a race boat looking for the extra 1/2 a knt

 This does illustrate just how critical it is to sort slip correctly, espec  before sorting pitch.




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Post Options Post Options   Likes (0) Likes(0)   Quote OneWayTraffic Quote  Post ReplyReply Direct Link To This Post Posted: 20 Apr 2021 at 2:19pm
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One disadvantage of rotomoulded boats is the relatively high drag as they go through the water. Not an issue at moderate speeds. 
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Post Options Post Options   Likes (0) Likes(0)   Quote Steps Quote  Post ReplyReply Direct Link To This Post Posted: 20 Apr 2021 at 6:32pm
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Another example of one is always learning..
Gone back of data of some smart waves and they also show similar weight bigger than should be.

Why would molded boats have a higher hull friction constant?
Alloys/ glass are all very similar other than a couple makes of alloy stand out a little.
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Post Options Post Options   Likes (0) Likes(0)   Quote OneWayTraffic Quote  Post ReplyReply Direct Link To This Post Posted: 20 Apr 2021 at 7:33pm
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I'm not sure. But it was sure true for mine. It might be that the material has a bit more flex in it. My one also had a bit of fuzz on the plastic.

As to the weight issue, that's usually the single biggest thing. The hull material for the SW3500 is 6mm thick with a full foam fill. The 4200 has 9mm I believe, also with foam. All dimensions being equal, plastic bends  a lot more easily than wood, glass or Aluminium. 

The Youngs modulus of stiffness for plastic is about 1GPa. Wood is usually about 12GPa, a typical woven mat glass layup a little less. Aluminium is 69GPa. So the hull needs to be thicker to give similar stiffness. And hence more heavy. 
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Post Options Post Options   Likes (0) Likes(0)   Quote Kandrew Quote  Post ReplyReply Direct Link To This Post Posted: 20 Apr 2021 at 8:27pm
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Less torsional rigidity ?
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Post Options Post Options   Likes (0) Likes(0)   Quote Steps Quote  Post ReplyReply Direct Link To This Post Posted: 21 Apr 2021 at 9:36am
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How accurate would the 250kg for the trailer be.. that a guesstimate at best?
 Been doing a bit of rough calc.. even with such diff in drag numbers, and also considering that it is onlt the surface area that is in contact with the water (the stern 1/2 or less @wot)
Still not having numbers add up.
 Which then leaves as far as I can see actual the trailer weight.
 And also considering how easy it is to lift these when they dont back up easy where you want... and how even larger trailers are reasonably easy to jump..

 Have been looking down several boat trailers, manufactures (off shore) and similar seemed consistent around 300 to 400lbs... around 150 to 180kg
 example here
https://www.karavantrailers.com/marine-trailers/boat-trailers


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Post Options Post Options   Likes (0) Likes(0)   Quote FizFisho Quote  Post ReplyReply Direct Link To This Post Posted: 21 Apr 2021 at 12:01pm
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Been eying up used 4200 hulls, so I could add the centre console myself and potentially a new trailer, saving some cost on a new 4200CC package. 

The 4200 really handles the water well compared to the 3500imo, pushing the water out.

I had the centre console priced and the chillybin seat they use can also be bought from other sites, being a quality US brand.

But I just never had a 4200 hull come through at a decent price to make it worthwhile.

So Im stoked to read what you have done as its regathered my interest, boat prices fall during winter so Im in no rush but in saying that there is a lot of spearfishing Im not doing without a boat.

We trying to fit the build in for under $15k, thats why sourcing a hull cheap was important. There are many ways to get this done.

Thanks for posting.
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Post Options Post Options   Likes (0) Likes(0)   Quote spin king Quote  Post ReplyReply Direct Link To This Post Posted: 21 Apr 2021 at 1:21pm
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have got a 12 pitch stainless coming which is a slightly smaller diameter
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Post Options Post Options   Likes (0) Likes(0)   Quote Steps Quote  Post ReplyReply Direct Link To This Post Posted: 22 Apr 2021 at 9:35am
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Slip is high , need bigger diameter/ grip.
 Watch trademe...most are over priced never move.. like most of the boats..
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Post Options Post Options   Likes (0) Likes(0)   Quote spin king Quote  Post ReplyReply Direct Link To This Post Posted: 25 Apr 2021 at 8:37am
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took it out yesterday in 15 gusting 20+kts on a short sharp chop heading straight into the wind and was very pleased with its performance, wot skipping across the tops of the waves and very stable in the swell
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