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Old 15 August 2017, 08:34   #1
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Country: UK - England
Town: Keyhaven
Boat name: Orion
Make: Bombard
Length: 5m +
Engine: Outboard Honda 50HP
Join Date: May 2017
Posts: 156
Good articles about boat design and weighting

Hi,
I've been a happy boat owner since the early spring and I've got plenty of use out of the old girl so far, I've been working through my job list and coming towards the end. the plan was always to use this "cheap" boat as an introduction and then once we know we enjoy ribbing and have learnt more about it all, we'd upgrade next spring to something bigger, more powerful and generally more exhilarating.

The boat I've got is just fine but it's not as fast as we'd like, topping out at 25knts, some of that is to do with the boat design, engine power and weight distribution I'm sure.

So, as I can be as clued up as possible for "the next time" - are there any online articles people can recommend covering:

1. Boat design, e.g. deep V, wide V, width options, impact on stability etc

2. Weight distribution, when getting the boat to plain, where is it best to have the majority of the weight e.g. helm further forward and passengers arft or the other way around etc?

I've down my RYA PB1 and PB2 but obviously I've forgotten this or were not taught it, any links are gratefully received.
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Old 15 August 2017, 10:07   #2
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Country: UK - England
Town: Southampton
Boat name: SMH Rib / War Shot
Make: Ribtec / Scorpion
Length: 4m +
Engine: 10hp Yam / 150hp opt
Join Date: Sep 2003
Posts: 1,942
RIBase
https://www.amazon.co.uk/Power-Boats...2809226&sr=1-1

I've got a copy of this and it's a fascinating read.

To summarise my Naval Architecture Degree:

1. More power and less weight = more speed.
2. Flatter bottom = more speed.
3. Deeper V = softer ride, but needs more power.
4. As you go faster the ideal location for the Longitudinal Centre of Gravity (LCG) is further aft.
5. Having an LCG aft makes it more difficult to get up on the plane.
6. Longer narrow boats normally give a better ride - but don't always perform well heavily loaded.
7. A wider boat will carry more weight more efficiently.
8. Tubes in the water at rest = more stable at rest, but probably more drag under way.

In summary for my needs:
Longer
More power
Deeper V
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Old 15 August 2017, 10:14   #3
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Country: UK - England
Town: Keyhaven
Boat name: Orion
Make: Bombard
Length: 5m +
Engine: Outboard Honda 50HP
Join Date: May 2017
Posts: 156
Thank you!

"Longer
More power
Deeper V"

Sounds like what I was after. I'm assuming the longer you go, generally the wider the boat is.
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Old 15 August 2017, 11:01   #4
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Country: UK - England
Town: Southampton
Boat name: SMH Rib / War Shot
Make: Ribtec / Scorpion
Length: 4m +
Engine: 10hp Yam / 150hp opt
Join Date: Sep 2003
Posts: 1,942
RIBase
Quote:
Originally Posted by BigE View Post
Thank you!

"Longer
More power
Deeper V"

Sounds like what I was after. I'm assuming the longer you go, generally the wider the boat is.
It doesn't have to be. Several manufacturers will build boats at a range of lengths, simply moving the position of the transom in the mould.
The longer boats have the same beam (width) but the longer length, and greater L/B ratio improves the seakeeping.
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Old 15 August 2017, 11:05   #5
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Country: UK - England
Town: Southampton
Boat name: SMH Rib / War Shot
Make: Ribtec / Scorpion
Length: 4m +
Engine: 10hp Yam / 150hp opt
Join Date: Sep 2003
Posts: 1,942
RIBase
In summary for my needs:
Longer
More power
Deeper V

The above is for my Scorpion. Great sea boat with plenty of power and a very deep V. Great for going fast into a head sea - it slices through it (Up to a point!).

For our work boat which spends lots of time tootling around slowly we have the Ribtec 585. This is wider in relation to its length so not so good in the rough as the Scorpion - but still has quite a deep V so isn't bad.
All the seating is aft so it takes a while to pop up onto the plane sometimes.
It's all a compromise.
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Old 15 August 2017, 14:46   #6
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Country: UK - England
Town: Waterlooville
Boat name: Tickler
Make: Halmatic P22
Length: 6m +
Engine: Inboard Diesel 140HP
MMSI: 235115642
Join Date: Sep 2015
Posts: 601
RIBase
The RYA Powerboat Handbook is quite good for general hints and tips.
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Old 15 August 2017, 14:58   #7
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Country: UK - England
Town: West Sussex
Boat name: Grey Mist
Make: Parker 800 Baltic
Length: 8m +
Engine: 2xMercury Diesel 170
Join Date: Oct 2002
Posts: 3,823
RIBase
The best book on the market is The Complete RIB Manual by Dag Pike. First published in 2013

The definitive Practical Handbook for all RIB Owners and Users

you may get a copy from here www.adlardcoles.com
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