Boats 'made' Easy

Class Schedule to the End

Angled Transom

these are three photos of the angled transom.  this post should be just after the stem sections and before the other transom if we are talking about a time line of when things were completed.  the transom angle here was created using a trammel arm, marking out ten degrees for our transom.  the corresponding line that shows in the very right photo is the angle on the transom in the profile view.  we then take the length of all of the lines from the ap and transfer them down in the the half breadth view as shown in the far left photo.  we then set up another piece of paper that is parallel to the transom angle that we drew in and draw a centerline and other gridlines.  from where the transom angle intersects every line in the profile view, we draw a perpendicular line across our piece of paper.  then we use the beams/widths from the half breadth view and measure the width of the transom (this whole step is the middle photo).  we then repeat the same process to draw the inner transom just marking forward on the profile view the width of the transom.  after this all has been done then we can construct the transom sections.

Calculation of Displacement

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this is a breakdown drawing of the body plan of my lofting.  for every boat you must calculate total displacement, which is the boats own weight plus anything that goes into it.  so in our case, we must think about the craft, fishing poles, shoes, a bag, the person and whatever else there might be.  the reason that we have tons of different shapes on the drawing above is for the ease in calculating the area of each one of those shapes.  you can see the stations labeled and then the shaped broken down into easy to calculate areas, i.e.: triangle, rectangle, and a crescent.  then i measured all of the widths and depths on the body plan. 

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this photo is all of the calculations that i did in excel. this is a photo of the screen because i could not get vox to import the actual document (it isnt supported or some such nonsense).  so in the first column you see all of the different stations of the boat.  the next is the half ordinate values - this is what we calculated using those numbers from the first photo (the random jumble of numbers to the right is those calculations).  the next column is simpsons multiplier of 141... but there must be a number for each station so the multiplier gets added... so if the boat has 4 stations, the multiplier is 14241.  our boat has 6 stations so the multiplier is 1424241.  the column labeled function is the half ordinate values times the multiplier.  then added at the underneath. 

simpsons rule states that the volume is one third the common interval times the function sum.  the common interval (ci) for our boat is 385 mm.  the ci is the distance between stations, it is always the same for a given boat, hence common.  i then multiplied by two because i had half ordinates, half of the boats area.  the very last step is to multiply that answer by 1025, which is the specific gravity of salt water (kg/m3)... then i got 90.164 kg/m3 as the boats displacement.

Transom Details

this posting is the details for the transom.� james accidentally said trammel at the beginning, but no worries, we are well aware of the difference.� the reason why we go into such depth when we are creating are lofting drawing is because it can greatly increase the speed of building the craft.� we are able to essentially completely prefabricate the transom and the stem sections and then fit them in perfectly as opposed to trying to fit it and then having to go back and remove a mm here are there.�

stem section detail

picture yourself looking down into the bow of the boat standing forward of it.� you are looking down at the stem and the material that it took to construct the stem section.� this video depicts the drawing of half of that view on flat paper... it can be hard to grasp the picture and the detail, but that is why i talked about what i was doing as i was doing it.�

then next photo is several of these done on the stem of my 2.5 meter dinghy.� with these sections you only need to do as many as you need that much detail, so this means, that if you have a very large boat and the stem angle does not change a lot then you wont need very many and can space them out a good distance, and vice versa.

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stem

Stem detail

this is the stem of the boat which is located at the bow.  this part is extremely crucial because it is how the boat will take its shape.  the reason why this part of the boat gets so much attention is because the typical batten will not bend up so steeply and so there are special rules to loft this part of the boat.  we will use a shorter batten that is also thinner and so we need more precise measurements because this could potentially throw off the oustide of the boat, especially if it is a larger boat.  what wrong dimensions mean to the entire lofted boat and not just the stem is that it could make the boat lumpy... and who wants a lumpy boat? 

Lines Plan: profile, half breadth, body plan

these photos depict me and my lofted boat.  in the photo on the left you can see the profile view and the half breadth view and just at the end of the paper is the body plan.  as stated in the lofting schedule post, this is where we actually begin in draw all of the different lines that represent our future boat.  in order to get all of the curved lines we use battens made of spruce and we nail them around our dimensions and then, after we had made sure they are fair ({fair meaning that it has a good curve and isnt lumpy), we draw our line for how the boat should be shaped.  this process is time consuming and tiresome because it requires that you be mentally astute the entire time that you are working, because if you make a mistake early, it could mess up the entire loft. 

lofting schedule

Photo(3)

this lofting schedule is basically us planning how we should develop our loft of the boats in the best way.  first we start pulling off the dimensions for the boat from the drawing in autocad and then we are able to begin drawing in all of the gridlines (buttocks, water lines, center line).  the most important thing in this step is to make sure all of the gridlines are completely square because otherwise it will through off the entire drawing, then the boat. 

why im in new zealand

Boat

this boat is actually italian made but it is so choice... this is why i i love boats!!

lines plan and a bit about lofting

next week we start lofting.  which is essentially planning out the specifics of a given boat and making certain pieces to scale to begin construction.  on the chalkboard we have drawn the lines plan.  the top have of the lines is the profile view with many of the lines drawn, sheer, load water line, chine, FP and AP, and centerline.  the most interesting thing is that in the different views, such as from profile (side view, starboard side) and half breadth (top or bottom depending on perspective) the lines are called different things - the deckline and the sheer are the same spot on the boat but just from a different view.  it is slightly harder to learn but it has great reasons because of how the boat is built it is considerably useful. 

the other photo is a small row boat type thing that we talked about.  we drew chalk lines on the boat to discuss the hollow that should be at the forward end and also how this particular boat is developable - only has one curve in the topside and bottom.  if the boat is developable that means that it follows either a conic shape or a cylindrical shape.  if you draw lines you are really able to visualize the concept.