saw this..., not a megles. https://lh5.googleusercontent.com/-...ical+scale+of+a+pram+5-22-2013+1-41-38+PM.jpg I woudl not even think to try to do a design based on pics... I guess you could always take a hull and make measurements and plot it out...
Not to get personal, but the plug looked a little "fat" compared with the scows we usually see up here. Ours, are wide, long and not very high freeboard. This one looks like what I was expecting. [click on image to enlarge] Dick
If you have a drafting background, old school method, you can use a side view and a top view - and can then "project" the cross section points to show the cross section template shape. Hard to explain, but easier to draw. Basically the top view is directly above the side view. A 45 degree line is drawn and lines from top view are extended horizontally, until the hit the diagonal line. Then the lines are dropped vertically. From the side view, the lines are drawn horizontally until they meet the dropped vertical line. This locates a point or dimension on the right side of the horizontal view, but begins to reflect cross sections, depending on number of lines "projected" from top and side view. More lines from different points = better and more accurate the front (or rear) views. Will see if I can do a quick sketch on paper to demonstrate. ADDED: Called Orthographic Projection, it is what we did by hand, T-square and triangle that the new software drafting packages can do in micro-seconds. Regardless - here is a link to an excellent graphic demonstration of the process. http://cms.cerritos.edu/uploads/dmussaw/projections and views.pdf Dick
Dick, the 747 is a mini transat its beam is about half its length. look at all the 6.5 meter transats they mostly all have wide hips.... so to speak... so not a skinny scow, by any means.... Yeah I studied marine engineering for two years and did a lot of hand drawing for some reason they loved having us draw gears...ugh ... the key to getting the other view. is data. good data means good drawing. so if you have a drawing or one set of lines to extrapolate the others could be done fairly easily. Do to this off of pictures...no so easy but doable. prone to errors but still. better than nothing...
Marc - Claudio .......... here is a link to a bunch of photos. I chose the C Scow, as it is uni-rig and might work better for an RG sized hull. The A Scow has the jib and huge spinnaker like in the previous image post. https://www.google.com/search?q=c+s...DsOTyAS66IAQ&ved=0CAkQ_AUoAg&biw=1017&bih=636 I think Doug Lord did this one - looks like some of his work - I recognize the moveable ballast system.
Dick, the scow hull has also very low bow unless is modified at model level. Even small wavelets will be seen as an heavy sea conditions. Easy to imagine the consequences ! In my opinion is also difficult to pass from a dinghy design where is the team acting as movable ballast to the same hull equipped with fin and bulb. The picture do not tell how complicate could be the electronics to control the shift of the ballast unless is a go-no-go or "centre-left-centre-right-centre" like at the begin of airplane Radio Control models. Who is going to tell to the ballast which side the boat is tilted as such to go in the opposite direction ? Difficult to immagine this application in a real RG65 race with continuos changes. To make it simple I would prefer to limit the swing of the main boom at 35°-45° with a single sheet without sail servo but only rudder ! It will be more funny to the point that I would suggest this option for real model's races. Cheers ClaudioD BTW : http://www.yachtingworld.com/blogs/elaine-bunting/531437/ugly-but-fast
popped it off. I pushed out too much epoxy. I can see some pinholes. the aft portions of the hull seem awful bendy... maybe after another day or so it will firm up some more. but I think I'll have to add some extra reinforcement to keep the hull in shape...couple that with some thin epoxy brushed on the outside to seal some pinholes before paint/sanding.. also need to figure out the deck. would love to make it look scale. also have the added dilemma of figuring the Lateral resistance. The original relies on canting keel and bilge boards... so I'm thinking of splitting the diferencne between the bilge boards and the keel..
got too anxious trying to work on the pin holes... sanded too much... hull #1 is now scrap... Iwill probably put it back on the plug and mark it up to removed a 2" section out the center to skinny it up just to see what it looks like.. so I worked on hull #2 I went with a heavier layer of glass, a layer of kevlar and then light glass. hopefully this will take care of the flex in the flatter sections of the hull..
In my experience pinholes should not happen at all! The order matters here: start by pouring epoxy and spreading it on all the surface. Do not hesitate to add more epoxy as needed. Just then add the first cloth, and make sure it gets soaked in epoxy from below! It there are parts not completely soaked, add more epoxy there. Continue with all layers this way. Finally, squeeze all epoxy you can out of the hull, removing it with a spoon or other tool. At this point you need to remove as much epoxy as you can. If you did it right you will have no pinholes. The latex method works the same, but makes the squeezing much easier! I've already built two hulls this way, and I have never ever seen a pinhole!
no latex, here. In my first hull I was just too aggressive with trying to make the hull as light as possible by removing excess epoxy. just squeezed out too much... eveyrthing was plenty wet no air bubble and dry spots.. so my though was to fill the pin holes with some thinned epoxy. brush it on and let it set and then sand and so on. too much epoxy got through the pinholes.. and the drops hardened inside the hull. I did not notice, and while sanding and applying pressure the resulting drops on the underside of the hull created the false high spots.........stuff happens... hull #2 will be ready tomorrow afternoon...so we'll see what happens... I'll do some light sanding and start the process again...
Put some Mylar tape (the brown one) on one side and pour the epoxy from the other. This will prevent the overflow.
I don't do the tape so I don't have ot worry about tape ridges. but I do cover the plug with a heat shrink plastic so I have a nice impermeable surface and the hull releases very easy from it as well, as good as it removed from the tape..
hull is about 1/4" away from its final trim size. and I spent some time working on the deck/cabin plug. still not sure how I'm going to do the deck access. The mast is deck stepped in this case on top of the cabin. so one option is to make the aft portion of the cabin removable or just go with simple tape... have to install the keel trunk first to determine keel access..which will also dictate my deck access...
Marc - apologies for my previous posts. I thought you were going for a traditional, inland lakes scow....... ie - a Melges or Johnson. My Bad ! On a different topic - What did you use for heat shrink wrap? I am applying veneer to an old "M" and found a few spots where keel wasn't too fair, so thought about using a coat of epoxy (after staining veneer) and using some of the big boat wrap we use up here in the winters. Problem is that it takes a lot of heat to shrink, is kind of thick, and I am worried about crushing the light original hull. Any suggestions appreciated. Thanks, Dick
no apologies needed dick... this is definitely not your "normal" scow... I use this type of heat shrink film... http://www.davpack.co.uk/polythene-packaging/shrink-wrap-film/pvc-shrink-wrap-film.htm able to use an electric heat gun, no flame needed. shoot me an email I'll pull a few yards and send it to you..
"This" will be interesting to see. A unique idea to try and an easy (sorta) class in which to do it. Next thing you know, it will warp over to the IOM Class and become the "design du jour". Seriously, wish you good luck on this one, Marc. Dick
Dick, Yeah I have no thoughts of grandeur...but it would be cool if it works... I wonder if the the wide nature of the hull will make the boat act more like a catamaran???