Hi All, I'm working on building a USS Northampton/Houston from an old swamp works kit. I'm working on taping the hull to cut the window in it and I'm having trouble figuring out how to deal with the sharply angled chine that is at the stern of the ship. I'm building to IRCWCC rules. I've looked at the builds on portpolarbear and looked through the threads and can't seem to find a clear answer. Do I leave a little bit (1/8 inch or so) of vertical material above the chine to adhere balsa to? Help very much appreciated! Frankly, any advice on marking or cutting this hull would be greatly appreciated. It looks like the max weight is 11.58 lbs, so I was going to load the ship to this weight to mark water line. -Thanks!
I had the same problem when I cut my Hamp. Balsa's pretty flexible stuff, so you can bend it pretty well and get it to hold the chine contour pretty decently. That Swampy hull should be a bit thin compared to the run of the mill boat around nowadays, so the little sliver of fiberglass you're suggesting to keep would just be part of the thicker bottom material. Don't take my advice as the 100%. I haven't worked on that Hamp in 17 years and that is the only FB boat I have ever touched. The person I would consult with regard to cutting that angle would be Kevin P. He knows the cutting rules like the back of his hand. take pics of the chine from a ton of angles, and see what he'd do.
Per rules you have to cut to the 45 degree point of the curve, which will pretty much bisect the angle of the chine. Balsa bends pretty well. You can also do it with two pieces, one piece on the flat underside, and one piece on the side the mates up at the curve, and put a couple pieces of sillspan over it. Pictures help in general for communication if you can post them. Overall, for a new person’s boat I wouldn’t worry about it too much. Pretty much all battlers are forgiving when looking over new peoples boats, mainly we want to make sure the boat is functional so you have an enjoyable battling experience, holes in the stern are rare in general, especially at that location on a cruiser For the weight, you might want to plan for a couple pounds under and mark the waterline at that weight. Then add at least 1 and 1/8” below the exact waterline to mark the bottom of the windows (1/8” to account for half of waterline width). I usually will go with 1 and 1/4 below floating point for a little buffer. The boat will perform better at slightly lower weight, and if you mark the hull using max weight and don’t leave any margin, and then decide to run it lighter, the boat might not have 1” of penetrable area below the waterline
Awesome! thanks all. I'm going to float the boat, mark the line and windows, and hen post some photos to this thread before cutting. Hopefully I can grab some feedback at that time too before getting myself in to too much trouble. As a question on construction, do you usually cover the entire hull in balsa (including the underside) or just the penetrable window sections?
HI All, I've tried marking up my Houston for cutting. The tape for the ribs is 1/4" tape. The boat length is 50.5 inches so I placed 17 ribs at 1/4" width and 1 rib at 3/16" at the step in the deck. I tried to generally follow the framework on Port Polar Bear for the FN Glorie (http://www.portpolarbear.com/reports/Rib layout of Glorie.htm) since this seemed to be a fairly similar ship design. The drawn on line going lengthwise on the hull about mid-way up marks the water line for the boat measure at 10 lbs (Max hull weight 11.5 lbs) with the stern deck level using a bubble-level. I put the bottom of the window 1.25" below the waterline. The tape marking the deck level is 3/8" tape. I'd love feedback before I cut. Thanks again for the help.
Looks a lot better than my Hamp's 10th grade hack job. (Don't take that as an endorsement though, I'm a wooden boat guy so hopefully FB boat guys weigh in and say something from experience)
Overall looks good, I think the window depth might be a little conservative, you can probably move the bottom of the windows up 0.25" along most of the length. The stern looks a lot less conservative (assuming you are cutting above the tape), the second to last window specifically looks a good deal above the 45 degree point, so probably move that down 1/8" to 1/4." Balsa is remarkable. Overall plan for 10.5 to 11 lbs based on where you drew the waterline (sitting pretty high at 10)
Thanks all for the feedback! I really appreciate the detail. The good news is I've got the cannon system, drive motors, pump and new steering/radio system up and running. I took another attempt at floating the boat and brought it up to a touch over 11 lbs (max weight 11.5 lbs) This brought the waterline 3/8" higher on the hull so I re-taped the bottom of the windows where they are defined by depth below the water line. The new waterline makes by the blue ink on the tape. the old waterline is marked by the line on the hull itself. The windows in the stern (where it is more defined by the turn of the bilge) didn't change much if at all. I move the tape in the last two stern windows down to where it rides along the angle of the chine. Please take a look at the new photos and let me know your thoughts!
