Self Righting

[electric]

Inspired by that other thread for the Carbon Titan. Has anyone successfully built a mono that rolls over that is 34" or longer? Is there a practical limit to it?

[NativePaul]

We have a class called "Supermono" here for 8s boats, most are over 34" and as far as I know everyone's Supermono self-rights, with the 6 minutes our monos race for self righting is pretty important, as you can gain a heck of a lot more than the roll over time by running the boat that much looser than you safely could otherwise.

The second boat in this clip is a Supermono and while Mark didn't slow the video down by waiting for the self rights you can plainly see the flood chamber on the left of the stern.

Self righting works at any scale, all our lifeboats are selfrighting (and I think your coastguard rescue boats too as there is a link to a similar test of one at the side of this video).

[electric]

Thanks for the videos! The mono boat race is crazy. Ok, so do you know of a self righting boat that is in Europe that is 32" - 34" long. The rules here dictate that the mono hull (P-mono) cannot be longer than 34". Might be interested in building one to race. I have always been interested in self-righting hulls, but over here there are only a few and they are smaller sized. There is one that is the correct size(Triton), but the hull is not really a race hull.

[NativePaul]

The Triton is the only one I can think of that would suit P-Mono, we are allowed steps in our monos so the vast majority of are Monos are stepped, Joseph at toysport is the only one I know of that develops both stepped and unstepped bottoms for his hulls and 32-34" is between our classes too, Mono2s are normally under 30" and Mono3/Supermonos are normally over 34". I wouldn't discount the Triton off hand as not being a race boat though, Joseph is a FE racer at a world level himself, and I have seen many competitive Syncrons and Tritons over the years, mostly stepped here but unstepped versions can do well in the rough, an unstepped Syncron won our Mono2 nationals in '11, and Joseph reached the Mono2 finals at the last Naviga world championships with an unstepped Triton.

I believe any Mono can be made to self right, as well as all the typical European and Chinese race boats that self right I have seen several cheap Chinese delta force style knock off hulls self righting with flood chambers, an SV27 RTR which is a horrible hull but self righted with a flood chamber and float (and needed to often, I'm not sure if the float was needed to make it self right as the chamber was too small or just to speed it up as it went over so often), and lots of scale Ocke Mannerfelt bat boats, with flood chambers. There is no reason you can not take your existing competitive P-Mono, gut it, fit a flood chamber, and rebuild with your cells off centre to make it self right.

PS, that was more than one race, footage was taken from 3 heats of Mini Mono, Mono1, Mono2 and Supermono over 2 days with Mark following the most unstable boats to get the best footage, unfortunately my missing a buoy with my Hydro2 was so rare that weekend that it was deemed worthy of inclusion despite nothing happening. Mark kindly credited me, but all I did was lend him a second camera which he set up static while he crawled on his belly doing the work, If you are interested in the Naviga style of boats or want to see some great photography from races check out the threads on here started by Mark Thompson.

[electric]

Thanks for the reply. I have owned both the Triton(2 of them) and the Syncron at one time. The Syncron is a great boat. It really carves a turn like crazy and is an excellent boat to drive. The Triton(for me) is a good boat and I had lots of fun with the ones I owned, but never really turned quite as well on an oval course for me. It tended to hop on turn and I could never get it to really settle down. Joseph is obviously a better driver than I. Of course, the build quality of both of those boats is without compare. Really nice work. I wish he made a "large" Syncron.

The tough thing is buying a perfectly good brand new racing hull and then cutting a hole in it and "Hoping" you have put a working sized flood chamber in it with no real experience doing so. That is why you probably don't see them that often.

[NativePaul]

Joseph has bowed to the pressure and made a larger copy of the Syncron, but it is 1500mm long for 25-35cc Petrol or 10-12s electric.

All the popular Naviga suitable racing boats ie:- ETTI, H&M, Rausch, Tenshock, Lindeneau, MHZ, Dr Psycho, have chambers built in or come with pre-shaped chamber walls ready to glass in, most of the rest of the boats are either Artizan boats from small cottage industries which sometimes just come with a template for the chamber, or are home designed/built with home designed/built chambers, we don't often see boats that don't come with a chamber in one form or another from the factory, but those we do see all end up self righting within a few meetings. If you put your servo and RX on the right side, batteries and ESC just to the left of centre and low down then shove a bit of cardboard in upright as far towards the centre as the batteries will allow and bend it to fit the hull, cut a piece of ply/glass/plastic/whatever around the template you just made than glass it in with some thin glass cloth, when dry cut out the transom on the left side of the chamber wall, mix up some thickened but still runny resin pour into the chamber and run around the seams, check for leaks in bath by leaving hatch open to see inside and pushing the chamber under water, drill holes into flood chamber to taste (more holes right it quicker), make RTR and place in bath upside down see if it rights, if not you can add weight to the flood chamber wall or add flotation to the top on the opposite side, boats generally have more lift on the bottom than downforce on the top so it does not have to flip right over, as long as it goes sideways enough to get the prop into the water you can give it throttle and its forward motion will take it the rest of the way.

Have a search on RC Groups, someone did a very good how to on flood chamber design and installation over there.

If you have glassing skills making a taller and rounded cross section deck will make it unstable upside down and it will roll over quicker than a chamber equiped boat but has the disadvantage of more aero drag and a higher CoG, they used to be more common but chambers are a better solution in most conditions and have taken over. there is also the old faithfull standby that works on pretty much any boat in a pinch, which is duct taping a large coke bottle down the middle of the deck (not an elegant solution, but it works).