Building Flareline 18, would like to extend by 2 frames...

Well I don’t know.

I think 2 would be the most.

Next would be 4.

I think 8 would have the least wetted surface.

But 1 chine could be configured as a narrow hull, if you add an outrigger.

I guess I would have to say 8 in general, it would certainly be more stable (less prone to capsize) in a narrow hull.

So yes 8.

 

Bert
I shan't comment on much of what has already been said - most, but not all, of which is absolutely correct - beyong reiterating in the strongest possible terms that THIS IS NOT A GOOD DESIGN FOR THE PURPOSE YOU HAVE IN MIND

I understand your reticence about spending more on another set of plans, but I can assure that this will be BY FAR the least expensive aspect of building your boat. It takes no more work to build a good boat than a bad one. Save yourself A LOT of grief and listen to the (unanimous) advice that you are getting here.....

 

You like to gloss over other parts of posts to make a point, don't you? Like the part where I added the fact that the boat was fully loaded for a weekend. That means full fuel, water, provisions etc......

Regards, Andrew.

 

Easy Rider

to get links to work you need to click on the blue ball with the chain link

then you get a window on top that says

"allow scripted windows" click to allow, now when you copy a link it will turn active when you post it


regarding the skin over frame type of build
why do i say old -
usually heavy to build
and very time consuming

I am a great fan of "modern" epoxy building tecniques as shown in

http://www.bateau.com/index.php

i also believe that they have a really good selection of plans for the amateur builder especially the guys that want to build "motor boats"

 

Guess I better respond to all this before I go to town.

Thanks Manie but where's the blue ball? True .. some (most) of the old designs are on the heavy side, still more efficient as they are narrower.

Andrew, I'm sorry ... I just hate over weight over powered boats .. and it's hard to find other good choices.

Sleepy,Well, if more's better (less drag) how can you say hard chines are such a drag. I thought that would be a cute retort but it seems a bit dumb now. One big thing I like about hard chines is their tendency to dampen roll with the turbulence around the chine. Then there's the water riding up the hull issue and hard chines are better at controling that .. much better for planing hulls. Just because soft chines are harder to build dosn't make them better.

Willy, We haven't heard from Bert for awhile ... maybe he's thinking.

Easy Rider

 

where's the blue ball?

below the smiley face to insert smilies
a window comes up = insert link
click it - then click allow scripted windows on top of your page (Widows XP)

 

Well, well, well, what a surprise. I am just back from Cape Town and went to see the University. They have some simulation programmes. I was flabergastsd to be informed that with adding 1 frame, after no 7, (No8) adjusted to the contours of the original design, that with the 2 x 4,5 Kw motors, the boat was even performing better. When they put another frame at no9, also following the contours of the orginal design, with as an exception, the that transom was slightly lifted as proposed by Rick, and even with the low power of 2 x 6 kw, it performed even better. However, with adding 2 frames, there was an 8 % higher chance to capsize the boat when waves were parrallel with the boat, in comparison to the orginal 5,3 meter design.

I don't anymore who to believe and what not to believe. Like somebody stated in one of the threads, NA has something in their sleeves, we do not know about, while computer programmes are as good as the input placed into the program. Rick, would you be willing to put the data into your program? If they are approximately the same as those of the university, at least we have confirmation and some direction.

I also have been able to get quotes for very light French marine plywood, which are excellent for this projcet.
i.e. 2500 x 1220 - 4 mm = 6 Kg , 6mm = 9 Kg and 9mm = 13 Kg, which are substantial better than the normal plywood.

My only problem is, like Piston so rightly said, God help those countries still battling it out with inches, feet and pounds. I have to waste a lot of material to cut the wood to the dimensions as per drawings. If I keep them in metric dimensions as available, the boat may get too heavy again.

I also visited the solarpanel manufacturer and they are willing to make panels for me, with special light surface and not hardened 3,2 mm glass. Although for 1Kw of panels it is only 10 kg difference and maybe not worthwhile. I like to ensure that the 20 years warranty ( in 20 years, 70% minimum photons conversion) will be met. Oh by the way, they informed me that another University is doing research on reflectors onto solarpanels. The conducting strips they are using, can carry 15 Ampere, while the panel only under maximum sunrays input are 8 ampere. That is good news for me.

Bert

 

Sorry folks, I was so excited, that I first put my news on the thread, before reading all the messages in the meantime posted. Cape Town is 420 km (267 miles) away from my house and I need 10 hours traveling time, up and down.

Well, we certainly have a divided audience. I like to explain something.

a) I am not planning to plane.

b) If I get too old and somebody buys the boat, he can put a smelly 60 Hp engine in it and do the planing. The hullt is then made for it.

c) I like the shape of the Fairline, and not the shape of the "London Themes" boats.

I hear what you say, that I am making the wrong hull. So what!!!
The speed is only up to 10 knots in anyway. I want to enjoy myself on the water, whatever hull I build, I may have to use 10% more energy to push the boat through the choppy water. WHAT choppy waters, I am not planning to go into the huricane situations anymore. That we did, when we did our off shore licenses.

d) I have to disappoint you all, I am planning to become a blue sea water boater and will make damm sure that the weather stays on my side.

I have bigger problems than the hull design. I have to prove, that the boat is floating under all circumstances, even with a big hole in the hull, buoyance is my problem.
Bert

 

Welcome back Bert,
I wasn't saying that you shouldn't build a boat with hard chines, I was just courious what the motivation would be. I think in a lot of ways it makes sense.

 

Manie,
Thanks. I'm going to get a new computer next month but I obviously need operational skills much more.
Bert,
I've come to the conclusion that you have no idea how much difference there is in power required for reasonable performance with full displacement hulls and planing hulls at displacement speeds. Full displacement boats only require 2 to 4hp per ton of displacement. Your 18' boat would displace at least a ton or more. You should get 5 knots w 3hp. To get 5 knots w a full planing hull like the Flareline 18 it may require 5 to 10 times the power. The latter is just a guess and I'd be pleased to be enlightened if I'm way off. Or am I behind the times as I am in my computer skills regarding power capabilities of electrical propulsion systems for small boats? Here again is the compromise boat.www.atkinboatplans.com Look at the boat Russell R.

Easy

 

Thank you Easy, But after I was in the doldrums for a few minutes, I started to think and my logic tells me that something is not adding up. I do not believe that if you have 2 hulls, both WITHOUT planing, that the one hull needs 3 - 4 Hp and the other 20 - 40 hp to move the same 1 ton through the water. I don't buy that. I am not rude, just that my logic tells me that I may need a 10% more power for the one hull (the badly selected hull) Yes, it is a different story when I lift the hull out of the water and start planing, then we need maybe only 0,2 ton to displace instead of a ton, and therefore need less power. But we all the time discuss a mono hull below planing speeds.

If I am wrong, I need to see a doc.


Bert

 

I don't have magic wand computer, but when I was growing up when John boats, or skiffs, as you might call them, for the same size they require ten times the effort to paddle as a 16 foot Hobie I owned later.

Take a look at Rick Willoughby's threads he might be the resident expert on getting every ounce of power.

 

Thank you helmsman, Yes I am pleased to be back at my home safely.

I am totally ignorant when it comes to boating language. What do you mean with a hard chine, and what is a soft chine.
Bert

 

You absolute right. I have great respect for Rick in the way he squeezes every extra drop of speed out of his hull , motor and battery. Unfortunately I am not in the same caliber as he is and I have to learn most likely the hard way. I may have to wait untill he has find the time to produce a full scale boatplan for his electric propulsed boat. I have received so many different opinions, that I have to sit back and do some analising.

 

Hi Helsman, did they really displaced both of them the same amount of water. i.e. both 200 kg or whatever??? If that is true, I better tear the boatplans up.
Bert