Looking for plans for very wide hull

I now have a triple crown, a Noux and I am looking to build a wide hull now. I have seen the Laurke which looks good but, Can anyone provide me with the drawings showing less shadows or colour code all of the shadow lines, it is hard to figure out where on starts and the other one start or can anyone direct me to another set of free plans for a very wide IOM?


Hi Andrew,

How about designing your own boat?

The Hullform program is a free download and easy to use.


I would not know were to start, but I might try to tinker with it as it will be a while before my wife will let me build another boat? To many things around the house to work on. Any hints to get going on this program will help?


I just found the Laurke lines on the R65 site, how much would i have to increase the scale to make it IOM size. Would it be enlarge to get 65 to 100? Would this work for all the other R65 plans?

Launch Hullform
Select File > New
Try these entries
Number of lines 5
number of sections 11
Overall length 10
max beam 2.3
transom beam 2.2
rake of stem 0
draft 0.55
stem freeboard 0.6
stern freeboard 0.3
Click hull type Yacht
Sectional curvature all rounded
Baseline pos Waterline

This will give you an IOM with length of 1M
beam of 23cm (same as TS2)
depth of 5.5cm (max allowed is 6.0, but wide hull does not need the volume)
Then click on the various icons to see the design.

Thank you John,
I will give it a try tonight when the kids go to bed.

That program works real good. But I have to say the info everyone provides here is better. John, what measurement do i put in for scale to print correct size? as well do you have any hints for static numbers? I can not figure that part out?

For the scale, I suggest a bit of trial and error. You know the beam. There is a rule on the page. Print off the page and then measure. A bit of calculation should help you rescale using the Configure > scale menu.

Here is the relavent text from the Help.

The scale value is the ratio of the actual size of the view (in metres or feet) to the size of the view on the page. If you do not like the default, any larger scale value will produce a smaller view on the page, with the required scale ratio. A smaller value will produce a view too large for the page.

A scale of around 1.3 should be close.

I have not used the Static so no ideas.

I think the RG-65 Laerke hull is just a scaled down IOM design anyway. It would need enlarging by 100/65. Most of the others were purpose designed and would possibly not scale up so well.

Scaling up or down has some pitfalls for the unsuspecting.
In the case of the RG to IOM there is a scale factor of 100/65 = 1.534 to one. Remember that you are increasing/decreasing the width, length and depth. That is a cubic change. Now cube the scale factor 1.534^3 =3.64. That means that the displacemnt of the IOM will be 3.64 times that of the RG.

The question is: Have the RG plans been done with a typical RG displacement figure in mind? If, in fact, the plans you mention are merely scaled down from an IOM then the Rg would have had way too much draft and the IOM would have been right. If the RG was designed to have the correct draft, rocker, and so on the IOM will float way too high.

This a classic bear trap that is not hard to deal with if you know where not to put your foot. Simply put, if you are scaling up you may have to decrease the rocker. Scaling down you will need to increase the rocker and in either case you will need to worry with the prismatic coefficients. Best deal is to use a program like Hullform and let the computer do the worrying.

Hi Again Andrew.

It’s been a while since I looked at Hulform so I am a bit rusty.

Here are a couple of items

On the COnfigure, Density of water, it defaults to 1.025. I think this is salt water. IOMs are to be measured in fresh water, so change that number to 1.0.

On Statics Settings, set the displacement to 4.0 kg. for the IOM

Also go to the AMYA site and to the US1M pages and download the designs ( zipped hud files) for the zipper 111 1v V designs. They are set up and you can see the parameters that were used.

Also, you can insert a section after 0 at about 0.15mm to get the bow frame shape and then from there to the front of the hull is the rubber bumper.