Normally I edit everything on my website. With Rudy's project I will only edit form and leave everything in Rudy's own words. I have to say though I don't know how Rudy could cut up a perfectly good hull :-) That being said, this could be the start of something that may affect us in the future in the hulls that we buy. Thank you Rudy for having the guts to do the R&D for the rest of us.
Read below and learn how Rudy accomplished this engineering feat....Enjoy!!
"Well, I finally completed my experimental self-righting boat project. I modified a 48" Aeromarine Challenger to have a "tide channel" that will allow the boat to flip over if it ever capsizes. You can see that I hacked a bit on this hull, making some holes and then covering them up again with duct tape.
In the end it worked great. The most difficult part of this project is trying to make the hatch fully waterproof. It still leaks a little, but the water drains out pretty quickly (using one of those much maligned auto-bailers).
When the hull flips over, water fills a cavity ("tide channel") on the port side and back of the boat. This shifts the center of balance and eventually the weight of the motor causes the boat to "pop" right side up. The transom drops getting the prop in the water and the forward movement of the hull causes all the water to pour out of the channel and off you go...
With this size hull, I think the port side of the engine rail didn't have enough volume to hold enough water to cause the boat to roll (or roll fast enough), so I had to move the radio box components to the starboard side of the engine rails and make the area in the back (where the radio box is typically placed) part of the channel. This allowed a lot more water to get in and roll the boat as well as drop the transom.
I routed the exhaust through the front of the hull. This part of the hull rarely touches the water (unless you submarine the hull). I used a flexible stainless steel gas pipe mounted to the end of the tuned pipe. The exhaust can be optionally routed to exit out the starboard side of the transom, since it doesn't get wet there either, but it's a bit harder to get it over there because the exhaust port on the motor is on the left. An additional benefit to routing the exhaust so it comes out near the bow is it allows the pipe to fit completely within the boat and you can use a 90 degree header. The standard configuration for an "in the hull" pipe is to have it exit out the transom, but this often requires a long "wrap forward" header to make the pipe fit, with several inches of the pipe hanging out the back. If the pipe is in the hull pointing toward the bow, you can use a shorter 90 header, which can increase the performance of the motor.
Another issue was getting proper ventilation to the carburetor. Good ventilation makes a big difference in the performance of a boat. Running with a hatch and very little air moving through the hull will really slow you down. I first tried a big vent on the top deck, but it was too easy for water to go in there when capsized. Instead I cut out vents in the freeboard near the nose of the boat. I over did it a little bit, but water never got in through the nose vents. To let the incoming air move through the hull, I also cut a hole in the right of the transom to provide an air exit.
The rollover process still takes too long (it's not a good idea to have the motor run upside down for a long period with no water going through the cooling jacket), so I think additional holes along the tide channel on the top deck will help the water get in there faster.
I plan on making similar modifications to a larger hull (Offshore Models 57" TeamStrike boat). I think larger area and freeboard will allow the "tide channel" to work without taking the radio box area.
I must credit http://www.rc-raceboats.de/ for providing some of the inspiration for this project"
**Click on thumbnails for larger view**
This picture shows the exhaust routed to exit near the front. The stinger of the tuned pipe was attached to a stainless steel "gas hose" (used for clothes dryers or hot water heaters). The picture also shows the starboard vent slots for the hull (a little bigger than necessary).
This picture shows the flood holes that allow the water to enter the tide channel. The boat needs more flood holes so it will fill faster. The area covered with duct tape is part of the tide channel. More water volume was needed to overcome the bouancy of the hull, so I used the area typically occupied by the radio box. I used duct tape to temporarily cover the area. I plan on putting a permanent aluminum cover there.
This shot shows the tide channel running most of the length on the port side. I used aluminum dryer vent sheets. Inexpensive and easily bendable. I needed to make a crease in the channel to make room for the header and the tuned pipe. Probably the hardest part was making the channel water tight. I had to use a lot of Marine Goop and I applied it to the inside seams using a long dowel.
Since I didn't have space for a radio box, I moved the servos to outside the starboard engine rail. The servos have been packed with dielectic grease so they are pretty much waterproof.
I had to tuck the receiver and battery around the stuffing tube. The battery was mounted on the port side to add weight and help in the rolling process.
The transom is cut out to allow the tide channel to "flush" when the boat starts moving. It also allows water to enter when upside down. When the boat stops/stalls upright, water does rush back into the tide channel, but since air gets trapped, the boat only lists a bit, but it doesn't sink.
This shows the two air vent holes for the tide channel. When water starts to pour in, the air has to escape. The hole above the "M" was cut first and probably doesn't need to be there. The one in the "yellow" really lets the air out. Being low on the freeboard also causes air to be trapped when upright, so the boat doesn't take on much water in the channel.
Vent holes on the port side. Again, too big. I plan on covering the holes with aluminum screen. Notice on the deck of the boat, I had cut an original vent hold. This worked, but it was too close to the water when capsized. If there was a little chop, the water would splash up into the hull.
Video #1 shows the complete powered rollover process.
Video #2 shows the rollover process with the boat un-powered.
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