So once I get back from the sandbox I plan to begin a new build. I am planning to purchase a fiberglass hull from strike. Up to this point the only ships I have built successfully are laser cut wood hulls. Specifically those done by Greg (his quality of work is amazing in my opinion). My question is two fold. 1) what's the best way you have found to determine how many ribs of either 3/8" or 1/4" are needed and marking them? Obviously the easy answe is trial and error but I'd like to be more precise. AND 2) easiest/best/most accurate way of marking location for cuts to install Skegs as well as holes for rudder posts? Obviously rookie questions to the experience fiberglass builders but this shall be my first attempt with a hull since my disaterous original swamp works Bismarck hull about 10 ish years ago. Thanks!
My method for placing prop shafts is to first figure out where you want your props and then work back from there. I usually stick the props to the hull with a couple of layers of foam double sided tape to space the props from the hull about an 1/8". With the hull sitting upside down on the bench, I eyeball and mark where the motors will be inside the hull (looking straight down on the hull). Draw a line from the center of the prop to the center of the motor on the bottom of the boat (as best you can). Now looking at the hull from the side, eyeball where the motor will be in from this view. Eyeball where the imaginary line goes from the center of the prop to the center of the motor. Mark that line on the bottom where the prop shaft and stuffing tube will penetrate. Now I cut a slot that will fit the shaft from the prop to the motor. You can now temporally mount the motor and prop with the shaft connecting them. Now its an easy enough process to enlarge the hole for fit the stuffing tube. If you take your time and do it right, you won't have to cut huge holes in the bottom of your boat that will need gobs of Bondo to fix. It's best to try to keep the motor, shaft, and props in one straight line (if you can). This reduces wear on whatever universal joint you may use between the motor and shaft (dogbone, etc). If you get the alignment perfect enough, you don't need a universal joint. Rudder locations are marked once your props are set in place. You want the rudders as close to the props as possible and inline with the shafts.
First get yourself some tape in the width of the ribs you can use/are interested in using (1/8, 1/4, 3/8) Figure out your rib allotment, if you're playing BigGun I recall you have a minimum window spacing but no % requirement, right? That makes it easy, mark a rib every minimum space, so if you can do a 3/8" rib every 3 inches, mark one every three inches. If you look at that and think, gee, i would like a litle more density of ribs, flip the hull around and mark the 2" per 1/4" rib or whatever it is and see which side you like better. Then rip the tape off the other side and mark accordingly. If you're playing IRCWCC you get 15% of your OAL solid. So if your hull is a short 50" OAL, you get 7.5" solid. You're allowed up to 2" solid up front in the bow (and allowed to follow the bows contour), and 1" in the stern (no contour allowance here) So assume you use the full 3 inches stern and bow, that leaves you with 4.5" available. You can break that down however you want, but most common is to decide on a rib size for the majority of your ribs. In this case, lets say we want to use 3/8" ribs. We'd get an even 12 3/8" ribs out of our 4.5". If you wanted to go with 1/4" ribs you'd get 18. Now, you can also steal from your bow and stern (bow most common that I've seen) if you want to make up a spare rib or two. Oftentimes in fast-gun, your number won't be so clean. You'll have some odd number like 4.65", in which case you could add a 1/8" rib, or steal 1/8" from the bow to make 1/4" rib, or some other variant. You can mix and match rib sizes so long as you maintain the 1" space between ribs. One last thing to keep in mind where you're marking a fiberglass hull - there is no requirement that I have seen in any format for you to put ribs on port and stbd in the same locations. Meaning you CAN shift rib locations to increase their density (so long as you meet minimum spacing) in areas you expect to take damage. Personally I like to run a increase the density near the bow at the expense of the stern. Some people will put more around sidemount locations, figuring that if they are on target, the other guy likely is too. One last last thing, if you're building IRCWCC, the rules allow you to extend a stringer to the next rib from the end of the feature that dictates its usage. In practical terms, this is now widely taken to mean you can get an extra few inches on a stringer by planning your rib locations with a mind to leverage that.
Preferred method of attaching balsa to fiberglass? Also do most install subdeck before or after cutting ribs out? Same question for for cutting slots for Skegs and rudder posts. Once again never worked with fiberglass hull and don't like redoing things haha
Contact Cement is my poison of choice. Don't do CA or you'll be chiseling and grinding that shit off later. @SteveT44 will probably suggest E6000. I think he has stock maybe since he tends to suggest it for most things. Locally we have a guy experimenting with a silicone caulk to attach the sheeting. That's an interesting idea, seems to work so far but not one i'm wild about because of the slow dry time. On a hull the size of the Montana I would probably install the subdeck before cutting windows. Not really a concern about space to work on that hull.
Yup, and stinky when you grind it. Weldwood is so much easier to use and faster too. The CA tends to wick into the wood and produce hard areas near the ribs , this produces large holes (not good).
CA is brittle, but it doesn't matter in this application. Once the balsa is applied it really doesn't flex enough to cause issue
