Material Options...

[spiel_mit_feuer]

i have plans to build a smaller yacht in the near future, 30-40 foot in length, and im having a hard time deciding on materials, i did find a steel round bilge design i liked, but i dont have, and dont know where to get the english wheel needed for making the compound curves in the metal plate skin... so, given the size (im not sure yet whether it will be monohull, cat, sail or power) but i was wondering for a typical monohull what sort of prices people here have been seeing in using steel, GRP, and cold moulded wood for construction on similar length boats?

[TeddyDiver]

The cost of the hull is rather insignificant compared to the total cost of a project in that size. So best to choose the hull material considering the ease of construction (for you of course) and the practicality in the intended use.
There are ways to to built fair steelhulls without huge machinery (but I'm not any steel expert) I'm building my 33' project from wood/epoxy and the hull expences are round 6000e (maybe 10-15% of the total cost)

[Ilan Voyager]

I'll make scream some but steel is not a good structural choice for boats under 60 feet.

Besides it's not an easy material to work, and compounded shapes (and english wheel) is for professionals. Good welding and fair (without deformations) shapes are almost beyond the skill of the common amateur builder, add the hard work of a good rust protection, plus the number of hours (and cost) of all the lining and insulation...As I have spent years in steel shipyards I'll add the noise and fumes.

On small boats (until 60 feet) wood and composites are better suited. Good composites are not so easy to make, and I find polyester and its toxic smell hateful. The residual smell, lasting many years, in some polyester boats is a good motive of divorce.

Plywood is good for some kind of boats, but I think that strip plank with epoxy and glass is the easiest and forgiving method for an amateur. It's practically impossible to have a disaster if you follow the designer's plan.
Little tooling is needed.

That gives an uncluttered inside without stringers, and further lining and insulation are not required unless you want to sail in the arctic sea.

For prices; in the GLOBAL cost of a ONE AMATEUR BUILT hull (a small part in the boat's final cost) wood if you are not using exotic woods is the cheapest, the cost of tooling may upset the apparent cheapness of steel, and composites can be expensive.

If you choose a multihull, forget metal (alu or steel).

[spiel_mit_feuer]

if i decide to go with a monohull sail itll be cold moulded wood of about 30 feet, but i was also considering power boats up to 40' considering i could get a more modern, more efficient power plant capable of crossing an ocean, and i was considering the 395 power sailer cat which plans for are offered by bruce roberts, if building a cat or power boat i was considering GRP, since they dont have the ballast a sailboat has, it wont roll over if it capsizes, so GRP or some sort of synthetic material i think would be best for safety, as the foam or balsa cores tend to float on their own.

[TeddyDiver]

Originally Posted by spiel_mit_feuer

if building a cat or power boat i was considering GRP, since they dont have the ballast a sailboat has, it wont roll over if it capsizes, so GRP or some sort of synthetic material i think would be best for safety, as the foam or balsa cores tend to float on their own.

I reckon most of the modern multihull designs have built-in flotation compartments. Many of the plans are also readily made for either coldmolding or strip planking technique with a monocoque construction so they are lighter than you can make with traditional cored/GRP construction..

[lazeyjack]

you can make your own wheels, somewhere in here is my design for plate wheels, forming and stretching speeds and all that
look in my gallery, ------
i, will help you by pm, but not in here


plate wheel machine and technique
look at this thread

[lazeyjack]

in this pic you can see how we do it in NZ, you may call it the NZ wheel!!
and yes steel is possible and very POSSIBLE in 40 feet, 4mm is best, but aluminium is better by far and as cost effective We proved that over and over
take a look at the Huisman and the alloyyachts sites, see what is poss in alloy, sure these are very expensive stuff, but it is very rare these days for a big yacht to be made in Steel

[Ilan Voyager]

Hey Lazy, he is a total beginner, look at his other posts...and you're talking of of Huismans (do you know this shipyard? have you seen their tooling? how many years of experience have they?) and formed alumimium...with the money needed for all the tooling he can buy a used boat, plus he will have to learn to make structural welding in alu...It takes years to learn metal boatbuilding. How many amateurs have f... their alu boats with bad weldings? As I have seen many times, the amateur results were ugly, if not useless. Plus you'll have to make all the insulation and lining.

Why not prepeg carbon fiber, nomex, vacuum and 40 feet oven to cook all that?

spiel_mit_feuer:Keep It Simple and Stupid (the KISS principle). Forget also cold molded wood; it's too long. I have the experience of that; I begin as apprentice in 1970 in a shipyard making cold molded wood; very tedious job. Make a search about faster systems; cylinder mold and variants in plywood and composites, Kelsall system, compounded plywood. There are a lot.

[FAST FRED]

Kelsall has a simple system for foam core that is suitable for amateur quick builds.

Basically the hull is laid up on a flat table , and curved to a simple form while still very green.

Saves loads of fairing and filling time compared to the male plug (Franz Mass) system.

Mostly suitable for single curved surfaces , simple catamarans or boats that could be built in plywood.

Not very cheap if quality foam is used.

FF

[lazeyjack]

yes I know huismans very well, i was simply trying demonstrate how well alloy is thought of thats all)

[lazeyjack]

and I would say, never think you can not do it, here is my first alloy, and my second yacht, I had no previous exp apart from doing engine rooms at alloyyachts ltd, for a month of so, I even built it upside down thats how green I was, but it was a perfect wee yacht 36 feet, so there you go, somewhere have pic of me plating it, I put a ply house on it, sailed like a witch, finnkeel,

[spiel_mit_feuer]

ive been doing more thinking and since theres not a boat out there of any realistic size for one person that can hold all i need for a lab, workshop, etc, so the boat i build will be for recreation, and to live on for vacations, so im going 30 feet, probably sail, either GRP or could moulded wood i think.. and itll be sailing mostly through the north see (so i should consider steel, perhaps radiused chined) but i think wood or GRP would be nicer.. wht do you think?

[spiel_mit_feuer]

wait.. are you saying i could actually get the plans to build the wheel neccessary to shape the curves needed in plate steel to build a round bilge style? if so then i would most certainly LOVE the ankon 40 offered by dixdesign.. i love that design.. round bilge is great for the better, smoother ride, the hull shape is narrow, and is actually pretty fast for any yacht of its length, and being steel, and being that fast is even better (based on boats already made from this design)... so that fast, narrow steel hull would be perfect for cruising through the north sea... so how thick of plate can these custom wheels handle? 4mm?

[Ilan Voyager]

Originally Posted by spiel_mit_feuer

ive been doing more thinking and since theres not a boat out there of any realistic size for one person that can hold all i need for a lab, workshop, etc, so the boat i build will be for recreation, and to live on for vacations, so im going 30 feet, probably sail, either GRP or could moulded wood i think.. and itll be sailing mostly through the north see (so i should consider steel, perhaps radiused chined) but i think wood or GRP would be nicer.. wht do you think?

30 feet is a realistic size (roughly boats costs per pound) Steel is to heavy for a small boat, and on this size it will be cheaper to buy a used GRP boat than to build one...you'll find a lot in Europe as Jeanneau, Beneteau and other have built them by thousands. The First 30 by Beneteau is a good boat.

If you want a custom boat, on plans by a serious designer, cold molded wood is a good material for a monohull, but you'll have to be patient. For example you'll have to use about 50 to 60,000 graps to hold the planks veneers while the glue is setting and you'll have to pull out the 50-60,000 graps! maybe more if the boat has some severe curves...and to sand and fair each layer...generally a 30 footer has 3 layers, so you'll have to sand; the inside, first layer, second layer and outer layer.

I feel already tired... Read the Gougeon Bros book. It's an indispensable investment for anyone planing to build in wood. That will give you a lot of good ideas.

I affirm that for a amateur builder, with limited financial means and skills, strip plank (with some tricks), epoxy and biaxial is one of the best systems.
The first trick is not to use Western Red Cedar, which is expensive and may give alergias to some, but a good straight light wood like spruce, white cedar and many other. That cuts drastically the cost.

Plywood with radiused chines may be interesting but complicated. Strip plank bottom and plywood topsides is very good (I made multihulls with this system and it's very cost effective for one off boats).

lazeyjack, the attached pic is very nice...and speaks for your ability. But I maintain that for an isolated beginner amateur, without any background of metal work, aluminium (and specially the structural weldings) are beyond his capabilities. PS I know very well the Huismans shipyard, and also some others in the field like Abekin & Rasmussen, etc...

[spiel_mit_feuer]

ive priced out steel for the 40' model (10'10'' wide), with a material list, the price of the hull and deck was about $6,000, which isnt bad at all for a 40' boat, so i may go that route, since steel can be welded under water for repairs, and itll be sailing mostly in the north sea, i can really use that steel plate... so IF i can make a wheel to shape the plate, id really like to go this route since its perfect for what id need it for