Help required on hulls

[Robert Hornby]

I am getting close to commencing work on Columbines hull which will be fibreglass with timber interior and decking. I have sketched up my thoughts on the hull design below the water line but I stress I have no sensible knowledge of this and am requesting some guidance on this aspect. If there is anyone out there who has experience/knowledge of hulls (the prototype was built in 1890) I would be forever grateful.

Robert

[Jayville]

Robert...I can't help but will be following with interest..always wanted to build a small steam launch...please show your progress...clem.   Tasmania

[michaelr]

 Free plans on this site may help you with frame design and give you a idea of what's required for a model steam boat hull.

http://www.john-tom.com/html/SteamPlans.html

Mike.

[Ramon Wilson]

Hi Robert - I would say you will need a bit more in the way of cross sections through the length of the hull for it to be fair. Try Googling - 'Lofting Lines for a boat hull' - Full size or model the principle is the same. Once you have the lines the hull (or form) is relatively straight forward to construct.

Not teaching granny here but are you aware you can build a fibre glass hull on the outside of a form i.e. you do not have to make a mould in order to make a hull - unless of course you want two of them 

Regards - Ramon

 

[steamer]

"From My Old Boatshop" by Weston Farmer would give you a lot of insight.

He always recommended a floatation model....You could do that one half that size in Balsa and test it....in the bathtub....and be pretty confident in what you would end up with...

Farmer describes this procedure in his book.   I used it when I built my boat.    It described it's behavior on the water very accurately!

http://www.modelenginemaker.com/index.php/topic,249.0.html

Dave

[steamer]

http://www.amazon.com/From-old-boat-shop-One-lung/dp/0964120429


You could probably find a copy cheaper if you look local...but that's the book.

Check the library

Dave

[Robert Hornby]

Thank you very much gentlemen for the suggestions and info. I will certainly check out the "From My Old Boatshop" at the library. My real question was more about the general shape of the hull i.e. basically curved as I have drawn it or more of an angular design with chines? I will draw up many more sections when I get the general profile sorted.

Another question for the moderators is where do I post the build log? It doesn't seem like it would  fit into any of the categories.

I am thinking the construction will take a couple of years as for me the best part of model building is in the actual building much more than the finished product. I expect this is true for many of us in this hobby.

I will be making a 'buck' out of high density polystyrene and glassing on top of that, I have a friend who builds model racing yachts using this technique.

Robert

[steamer]

Generally Robert, a length to beam ratio of 5/1 or 6/1 is a good start with a low powered steam boat.   4/1 will work as well.

As a old very experienced boat building once told me.....with small boats...if it looks right...it probably is!

The test tank model built half that size will tell you everything you need to know...on a numeric level...not just opinion.   Check out the book....a good read!    The guy is really funny too!....

Dave

[stevehuckss396]

Another question for the moderators is where do I post the build log? It doesn't seem like it would  fit into any of the categories.

Sure it does. How about the "Vehicles & Models" section.

[Ramon Wilson]

I will be making a 'buck' out of high density polystyrene and glassing on top of that, I have a friend who builds model racing yachts using this technique.

That's exactly what I meant - sounds like you are in good hands 

Sure it does. How about the "Vehicles & Models" section.

Good idea Steve - that's where mine on the 'Wide a Wake' is Robert 

Regards - Ramon

[crueby]

My real question was more about the general shape of the hull i.e. basically curved as I have drawn it or more of an angular design with chines? I will draw up many more sections when I get the general profile sorted.
Robert

Hi Robert, one thing to keep is some flare outwards in the cross section around and above the waterline. It helps the stiffness, as in resistance to rolling, of the hull. Carving from high density foam and glass cloth with epoxy over that is a great way to form up the hull. Just be sure to have insulation around the boiler and engine, since heat over 150f can start softening the epoxy glass layers.

[b.lindsey]

Vehicles & Models works for me Robert. It is a vehicle after all, just goes on water rather than land or rails. I am looking forward to following along.

Bill

[zeeprogrammer]

Vehicles & Models works for me Robert. It is a vehicle after all, just goes on water rather than land or rails. I am looking forward to following along.

 

Excellent. I was hoping it would get posted. Looking forward to it.

[10KPete]

Robert, if you harden up the bilge some and carry that aft and forward it would go a long way to improving initial
stability and give much more volume in the hull for machinery as well as increasing displacement to carry that load.
I think the shear is a bit much also.

Have you looked at any of the steam launch sites yet? Many have lines for these boats.

Pete

[10KPete]

Robert, here is a link to a very good boat designer:

http://store.gartsideboats.com/collections/steam-launches

This page has some nice boats. If you click on a design you can see an enlargement. In the lower left of the enlargement are a
couple of little squares which, when you click on them, will give you an even bigger pic. Take a look at the lines and you can get
a good feel for the classic shapes...

Pete