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[MarkScratchBuilt]

Hi all,
im currently building my second scratch built boat, this time a yacht. I built a 1:72 scale of HMS Richmond out of ply which was very slab sided. A few teething problems, ok in the bath but once out in the elements not too good!
 
So, i am building my yacht using 6mm mahogany planking and thinking of fibreglass matting the outside to give it weight and strength? Is this the best option?  Or just coating the outside in resin?
 
Any advice would be appreciated!!
 
Mark

[derekwarner]

Welcome on board Mark........
You don't mention the scale of your newer or second model...but if the scale was the same as the first @ 1:72....your 6 mm thick model hull planking would be in real life [6x72 = 432 mm thick  ]
So without knowing some simple points here...if your vessel were 1:72....6 mm thick planking is grossly over thicknesses and again without knowing the style of vessel......planking thickness for this scale of 1.5 mm [thick] may be more practical
OK.....have I missed the boat here? ....or are the planks 6 mm high?...........in most build cases when we nominate a hull planking/sheathing dimension it usually relates to thickness.......
Certainly there are pros & cons with matting & glassing the outside verses glassing the inside
There are a number of excellent planking build threads here on Mayhem  ...........would certainly be worth a few long & enjoyable hours reading them
...... keep us posted with more questions as needed as you progress.....Derek
 

[MarkScratchBuilt]

HaHa sorry Derek    i meant 6mm wide, 1mm thick! Its going to be a long keeler double mast, 1:72. I shall have a read on the other threads. 
 
Is their a calculation to work out the ballast ratio? or just keep piling it in until it sits right on the waterline? 

[derekwarner]

That's OK Mark..... ...but using 1.0 mm thick planking as the base plank material ...can lead with sanding [to smooth out any convolutions] to a thickness of say 0.4 mm  thick
It really depends on the accuracy of your hull frames & the planked surface to determine the required surface removal to clean up
With respect to your ballasting question......at this stage    only you can answer this question
Keep us posted with images & possibly a little more detail of the actual plan & construction detail.............Derek
 

[Neil]

Mark........you'll find that using mahogany or any of it's dirivitives (sapele, 0beche, etc) hard to use as planks at such thin and narrow dims........Billing Boats used similar many years ago and it taught many a modeller to give up and throw the model away they were so bad.
Problem with this timber is that it is a "short grained" timber with the grain often running across the plank rather than with the run and as such snaps off at the ends very quickly and easily whilst trying to bend around bow and stern, even after soaking and steaming.
 
you would be far better using something like lime, cherry or similar long grained timber that is nice and soft to carve and sand.
neil
 
Welcome back derek.....been on holls matey.   missed your posts.
 
neil.

[tonyH]

Hi Mark,
 
Sometimes it's even easier to use hard 3mm balsa sanded as needed and then skin with thin tissue/resin. I've certainly used that on hulls as long as 1.5 metres. I even use garden fleece instead of tissue on the outside purely because its easily gettable.
 
Good Luck
 
Tony  

[oldiron]

Hi all,
im currently building my second scratch built boat, this time a yacht. I built a 1:72 scale of HMS Richmond out of ply which was very slab sided. A few teething problems, ok in the bath but once out in the elements not too good!
 
So, i am building my yacht using 6mm mahogany planking and thinking of fibreglass matting the outside to give it weight and strength? Is this the best option?  Or just coating the outside in resin?
 
Any advice would be appreciated!!
 
Mark

  Mark

 The chaps around here use very light weight fiberglass cloth when they resin a hull. Its not so much adding weight to a hull, but it adds strength. It also helps in suspending the resin when you're making the application, so less dribbles through any cracks and seams. The cloth can aid in giving you a smoother surface as well as a stronger one. Instead of using a brush for the resin application, use a small roller and start at the keel and work down to to the gunnels (the hull will be upside down). Do all your rolling strokes in the same direction. You can trim off the excess cloth at the gunnels when the resin has set up.
 Many of us also resin the inside of the hull too. After the prop shaft tube is installed (if you are using one), mix up some resin and pour into the hull. Then pick up the hull and move it around allowing the resin to flow through out the hull and get into all the nooks and crannies. Make sure the area where the prop shaft tube penetrates the hull is well dosed with the resin.
  When done, sand an lightly fill low areas on the outside of the hull and finish with your desired paint.
  After this you shouldn't get any leaks in your hull.

John

[MarkScratchBuilt]

Thanks guys! So i need to change my mahogany for either lime or 3mm balsa and fibre glass cloth or use fence matting for the over lay. I cut out my main structural pieces today so will post pictures as it happens. 

[MarkScratchBuilt]

Update!
I managed to swap the mahogony strips for 1mm thick balsa sheet which ive cut into 5mm strips and planked the port side of my yacht!    looks ok, better than my first creation, its actually starting to look like a boat!
I have a question though. I need to bulk out the long keel im thinking of using foam / Oasis from a florist mould it into shape then glass in with the rest of the hull? Does anyone have any suggestions or ideas? Thanks. 

[oldiron]

Update!
I managed to swap the mahogony strips for 1mm thick balsa sheet which ive cut into 5mm strips and planked the port side of my yacht!    looks ok, better than my first creation, its actually starting to look like a boat!
I have a question though. I need to bulk out the long keel im thinking of using foam / Oasis from a florist mould it into shape then glass in with the rest of the hull? Does anyone have any suggestions or ideas? Thanks. 

 i might be concerned with the reaction of the fiberglass resin on the foam. I've use block balsa wood to fill in large areas as you suggest or fantails on some vessels.

John

[MarkScratchBuilt]

Thanks John, block balsa it is! 

[pompebled]

I planked the port side of my yacht! 

I have a question though. I need to bulk out the long keel im thinking of using foam / Oasis from a florist mould it into shape then glass in with the rest of the hull? Does anyone have any suggestions or ideas? Thanks. 

Hi Mark,

Unless you have a super strong frame, working on just one side of a hull tends to cause warping, as a rule of thumb you add the planking evenly on both sides.

If you work with epoxy resin, using insulation foam works fine, glassing it with glasscloth is no problem.

If you work with polyester resin, balsa is the way to go.

Regards, Jan.

[Circlip]

Never use oasis foam in a boat, it sucks water up, clue is in the name. Expanded or extruded polystyrene or Urethane foams for flotation or blocking and are not affected by Epoxy resin but are dissolved by polyester resin.
 
  Regards  Ian.

[Subculture]

Urethane foam is not affected by polyester resin unlike polystyrene foam.

[MarkScratchBuilt]

Hmm ok i might still stick with the block balsa idea. Not sure about the different polystyrene reactions etc...    does anyone know where i can get cheap, good quality model fibreglass and resin off the internet? 

[triumphjon]

im using factor o , limberline spur in portsmouth for my resin and chopped strand matting , tissue matting i buy from henleycraft , both have outlets in portsmouth

[MarkScratchBuilt]

is aircraft tissue easier to apply than glass? because i might go that route instead...... 

[tonyH]

Personally, I've found the fleece easier to use. (a) because it it tends to tear less and (b) because tissue can tend to stay flat and not follow curves as easily.
I use 2-3 inch wide strips of fleece laid diagonally on the hull and tacked in place with spray adhesive before stippling on the resin to suit. Probably wrong but it works for me
 
Good luck.

[MarkScratchBuilt]

ok cool is that just normal garden fleece?

[tonyH]

That's the stuff
 
Once the first layer is on, you can add a second in the same way, just diagonally in the opposite direction.

[MarkScratchBuilt]

ok thanks i think ill have a go with that! 

[MarkScratchBuilt]

Progress. Both sides planked (laid out on an mdf frame so it is fairly strong, no warping thank goodness!) Ordered my garden fleece last night and have some epoxy resin ready to go. This ones slightly bigger than my previous boat so the better half is concerned!!  I shall upload a pic for whoever is interested.

[MarkScratchBuilt]

I have another question. Once ive glassed the hull, what should i do about a deck section and how would it be fixed to the hull? 

[MarkScratchBuilt]

Here is my first scratch built model of HMS Richmond with no plans.....

[MarkScratchBuilt]

Here is my first scratch built model of HMS Richmond with no plans.....

Its very high sided and flat bottomed with a small keel so it isnt too good in windy conditions, but for a first attempt i think its alright. Currently building my scratch built schooner with no plans pic to follow