Replating a steel hull and deck/superstructure.

[john connell]

DeepFrz,

Hi.Yeah I know- I'm a junkie ALREADY.
Here I am sitting here at 0600 reading more threads/discussions etc.
I should be on my way to work.
By the way do you guys have any particular advice on rubber type for safety reasons.? i..e bounce and surface feel.

Thinking of building myself a little rubber room in the workshop near my project so I can go and throw myself around it now and then because I am darn sure I'm going to need one.
Sort of like a time our room.

Maybe I'll start something here.?
"Rubber room of the month .
Send us your photos -Best tantrum wins a free box of rust.

Cheers

John

[Dean]

Im not sure but you may have cracking problems with your welds on railroad rail,it is different hardnesses here and can be problematic welding.plus it is work hardened from use.It wouldnt be good to have it fall off . Maybe try the American welding society site for more info. I have been welding since 1978 but still consult others when something isnt typical. Goodluck ,its quite a project. Dean

[Alan Wheeler]

Railway iron requires a low hydrogen rod to weld it. However, Standard MIG wire will also handle it. But I am not sure which is the better Gas choice, but I think Argon would be the better choice. The best rod is a Philips 56S or any other manufacturer that cross references to that. They are not easy rods to use though.

[john connell]

Hi Dean,
Thanks for your welding experience input.I have put out the idea of using rail welded to the fin keel in the forum because it probably hasn't ever been used as a ballasting process before.Worth a try and it is bloody heavy at 60 kg per metre. Welding the flat foot ( not head hardened section ) of the rail base to the fin keel should really not present too much of a problem as it stands but take on board what you are advising.We have a few "rail scientists " and metallurgists here at work who ultrasonically test rail and welded joints etc and know the rail consistency as experts.Will give it a bit more investigation before I go further.The best part about it IMHO is the cross section would not represent a wide drag/flow issue as per against enveloped/plated keel.

It really is outside the box ,but sometimes it is good to look at different ideas.Having said that if it doesnt stack up and enough people blow holes in it it will be straight to a conventional keel for this newbie.-stat.!

Wheels, As time goes by and the more I see of your informative posts I wonder if you are'nt really a professor of sailing posing as a humble yachtie.?The painting post was a beauty.Got heaps just from that one alone.
Thanks for your advice.Going to stick by MIG and Argon all the way.
Using a 200 amp single phase for general spot welds /stitching and a 3 phase 350 amp for the full flow hull welds.Luckily for me I have a very competent marine welder giving me a hand-and some lessons.

Cheers to all.

John.

[Dean]

That sounds good ,,ive seen lots of laminations in rail here but if you have a ut man that is a real asset. Goodluck

[Alan Wheeler]

Wheels, As time goes by and the more I see of your informative posts I wonder if you are'nt really a professor of sailing posing as a humble yachtie.?

Probably more like a Jack of all trades and an expert of none. Some would say I know enough to be dangerous :-)

I am not entirely clear on the use of the Railway Iron. Is this as ballast internally in the Keel? What did the plans call for? lead or ??? You see, it is what weight and where the weight is placed that works out your boat balance. Right down to even how the boat rolls and pitches. Realise that your boat movement is all about angles, pivot points, levers and motion. Hull shape causes a boat to want to pivot around certain points. Water force wants to move the hull and so it tries to pivot around those points. Ballast combined with weight distribution set the way that boat then actually moves around those points. If they are not what the designer originaly intended, then the boat can set up a poor motion and even a motion to extremes in some conditions.

[sandy daugherty]

John, I got the impression you intended to weld the rail to the bottom of the keel. Looking at your original photos I don't see a fin keel. Are you planning a full length keel? No objections to that, but its seems your boat is getting very heavy. It will take a lot of sail to get it moving, and that requires a lot of crew to handle it in even moderate winds.

What kind of keel do you plan?

[john connell]

Hi Sandy,
Before I start-loved your post on fixing engines-What a hoot.!!
Re your query on the keel.
Maybe I should start again with this.
They call me " He who knoweth nought about keels "!!
Your dead right it does not have a " fin keel ".That's what I called it though .At present it is simply a 5/8 inch thick ( I think ? ) steel plate running along/into the bottom of the hull.Full length most of the way at heights ranging from approx 1.1 mtr near the rudder then dropping down to 200mm at front.
What I was thinking of doing was welding rail at 90 degree right angles to the 5/8" plate along the length.Probably could manage to fit 1x 7mtr length plus 1x 5 mtr length along the plate on each side of the plate below the hull at lowest point possible.
This would give me a total of approx 1400 kilos rail weight. The boat was approx 9 tonne when taken out to put on the hardstand.I know it can be done welding wise but just not sure of the practicality.It should maybe not present a great deal of drag because of the low cross section when sailing.
Maybe this idea is too far out there and doesn't make any sense.?

Anyway, it is just a thought at present and I am keen to get opinions.
If it all seems like a "pie in the sky" idea in the end I will go to a normal boxed in type keel ( not full length though ),use the rail and other steel punchings and concrete it all.
Will gladly take other suggestions .After all I have plenty of 5mm steel plate to play with.
I am really interested in types of keel design and in general just want to understand the dynamics.
My aim would be to not have to rely on a lot of crew as you say.

Thanks very much for your comments.

Regards
John.

[Kijima]

Hi John
Having done just about what you are doing I would suggest keep the deck at 3mm thick and think of the detail of finishing off the ceiling where the deck meets the hull as that can always be an awkward detail . Try to keep the weight towards the rear of the boat or you can wind up with a boat that is nose-heavy. If you are going to cruise you will need 12mm chain and that too wants to be kept as low as you can go. Your boat looks fine without thew addition of additional steel there just look at where the boat is beamiest and that is where you want the weight to be. When you live with a project fore a while you will find where to place things. Most important you don't want too much weight on your deck. Also try to get the boat on an even keel you will then be able to get a feel yourself. I recently sold my 42 foot steel sloop after doing several trans-atlantic trips and when you load up your boat with stores youwil want to have the most storage space low down at the beamiest point or just slightly aft. That is the most comfortable passage-making stowage.
regards

[SabreKai]

I would stay with the 6mmx50 for framing. Also don't go beyond what the original plating is either.

I have a Roberts 38 which is framed in 5/16 x 2 1/2 flat bar and its plenty good enough. 5/16 is just about 8mm. My plating is 1/8 which is a tad thin at 3.17mm.

My old engine used to be a Volvo Penta MD 17c which weighed about 780lbs. I replaced it with a Beta Marine 38hp and saved about 3070lbs. Now the old engine mounts straddled the gap between two frames 8 and 9 and were as solid as a rock. The new engine straddled a frame so I put fore and aft stringers between frames 7,8, and 9. The mounts now weld to those and the engine is even better supported.

The interesting thing about my boat is that someone decided to double plate the rear half. From frame 7 back to past the rudder she is plated with two layers of 1/8.

She also draws about 14 inches more than she should according to the design drawings.

I would not attempt to change the thicknesses of anything unless you want to mess up the trim. i wish I could get that second layer off, but it would be a nightmare. At some point I will end up replating and I'll have that done in 3/16 or 4.7mm

[bobconnie]

Ive seen a bunch of smaller steel fishing boats that had rail road rail added to there keels to help the boats out in the seas of the PNW ! Most of them ended up with a real bad action in following seas they would pitch ya out of your bunk even when the seas were just normal !! The rail stayed on fine with SS rod. Just messed up the boat for comfort LOL Just my 2 cents

[minaret]

I'm guessing this job was completed about three years ago, since it's a four year old thread Kijima responded to in his first post. By the way, welcome to CF Kijima.

[Kijima]

Thank you minaret I will remember to check dates. As a newby there is an usher-in period which clearly I am still in and, I am hoping that the project is completed. Steel has a way of holding you up especially if you are unfamiliar as I was when starting out.
peace +

[MacG]

%mm plating for a 13 meter boat is not unusual. 4mm would do but 5mm is quite ok. The added weight is 7,8 kg/m2. Not that particular substantial.
The steel you should use is minimum ST 37 - better will be ST41 or Lloyds grade A - but 37 will do.

Testing steel is quite simple: put a strip of sheet metal in the vice and hammer it in a 90 degree angle to left and right. If there are no visible haircracks in the bending area, the steel is more or less ok to use.

In Holland steel yachts are very, very common and the workmanship here cannot be equalled.

3mm steel plating is too thin, depending on frame distance but in your case I would stick with 5mm. Wider and/or thicker strips for the frames are no issue.

I see that you have no real experience but ask some advice from local boilermaker, if any.