Rear Hydro Sponsons

[Joe Warren]

Albert is onto the real fix .......take the Ski ramp off the boat........

 

[Bob Willner]

Okay...I also have a Gas JAE that is almost ready to go. So, take the ski off,put on a set of rear sponsons and put non trips on the front? Will this make the boat run?

 

[Joe Warren]

Bob From What I have seen If you plan to heat race it.... YES!!!!!! Maybe Albert will talk about his Gas JAE?? it is a cheap entry level boat that allows scratch building again. But it needs help if you plan to heat race it?

 

[Michael Costanzo]

So we buy and meticulously build to the letter, a hot design .... and then just throw on an extra 5 inches of hull for the crack ??

Now this is really sense of humour testing stuff !! ...... :wacko:

there is no testing! the reason the japan racers never had good luck with the bigger boats and the always hopped and had all sorts of problems was the tub length. i spoke to a well know boat builder and we disscussed this for many days before making the hull longer. the "hot design" as you call it only works for the smaller boats and was never tested on the bigger boats. i have been in model boat racing over 30 years, do not race much any more but if boats are running good,i will run with anyone out there. if you need proof, i will post some pics from early namba nats with the gold in hand.

Mike you cut the last 3 1/2 inches off that ramp and you will be surprised how well it works too. if you add Anti trip to the front sponsons Skin the top of the sponson over onto the addon anti trip. the JAE works well in the water by itself. But the SKI ramp ( its prop plaining surfae) it the 1st thing it bumps its ass on in heat racing water & unhooks the prop.

joe,i have a small trick that i tried,i have a "U" notch about 1"or so behind the stut on the ski that so far has took the hop and prop unhooking away.i am thinking that this kind of allows a flow or release of pressure around the stut area? also could someone post a pic or 2 of anti-trip set up and does this take away or upset any of the turning capabilaties? PS, i am willing to try anything in this hobby.i think that is half the fun of it,when you stumble onto something that makes you go "holy sh*t". that is why i still love all R/C hobbies! LONG LIVE NITRO!!!

 

[Dave Wardle]

No questioning of methods or experience ... just a little disappointing to be 5 inches adrift if thats the case .

So far this boat has had over stock .

1/8th toe

Trued up turn fin (a little twist along it)

10mm thick aluminum strut (original non zipp version was twisting under load)... this improved matters a lot

Anti trip to both sponsons... this improved turning considerably and also reduced the ride attitude a little ... guessing due reduced running surface.

Slotted the last 2 inches of ski to drop the strut lower..... this prop drop is the biggest single improvement .

For tomorrow... a new two angle, slightly deeper ski (to accommodate deeper prop setting ) this will have a 1 degree main ramp angle.. and will be double sided taped on initially as the plan is to play with a slight offset too to counter the designs natural right hand turning .

One big help would be sight of the V2 drawings for this design.... The kit is very accurately cut and easy to build well. The question at the minute is the asymetric sponsons and their design angle . Currently 3 deg LH 3.8 deg RH.... this isnt a build error , the sponson profiles are cut different by 1/8th in depth giving the 0.8 degree difference.

 

[Dan Ellison]

How wide is that gas boat? You can narrow the overall width and it will load the rear a little more. Think of it as a triangle, the relationship between points make a huge difference on load and how weight is carried. I don't know what the afterplane length on that hull is but if I had a gas one I would swop the radio and fuel compartments(put the radio gear in front of the engine)

 

[stan simpson iv]

So we buy and meticulously build to the letter, a hot design .... and then just throw on an extra 5 inches of hull for the crack ??

Now this is really sense of humour testing stuff !! ...... :wacko:

there is no testing! the reason the japan racers never had good luck with the bigger boats and the always hopped and had all sorts of problems was the tub length. i spoke to a well know boat builder and we disscussed this for many days before making the hull longer. the "hot design" as you call it only works for the smaller boats and was never tested on the bigger boats. i have been in model boat racing over 30 years, do not race much any more but if boats are running good,i will run with anyone out there. if you need proof, i will post some pics from early namba nats with the gold in hand.

Mike you cut the last 3 1/2 inches off that ramp and you will be surprised how well it works too. if you add Anti trip to the front sponsons Skin the top of the sponson over onto the add on anti trip. the JAE works well in the water by itself. But the SKI ramp ( its prop plaining surfae) it the 1st thing it bumps its ass on in heat racing water & unhooks the prop.

Now you have a RR...If you are gonna do all these changes to the boat,why dont you just get a RR. JMHO. If you want to run the JAE style call the PEOPLE WHO run that style of boat,you might be surprised they might be able to help you. Boats are different weather it is a mono/rigger/sport/ scale /cat..etc. Everybody likes to set there boat up there own way,like they say...if you have a problem with your build...read the instructions.

 

[Michael Costanzo]

So we buy and meticulously build to the letter, a hot design .... and then just throw on an extra 5 inches of hull for the crack ??

Now this is really sense of humour testing stuff !! ...... :wacko:

there is no testing! the reason the japan racers never had good luck with the bigger boats and the always hopped and had all sorts of problems was the tub length. i spoke to a well know boat builder and we disscussed this for many days before making the hull longer. the "hot design" as you call it only works for the smaller boats and was never tested on the bigger boats. i have been in model boat racing over 30 years, do not race much any more but if boats are running good,i will run with anyone out there. if you need proof, i will post some pics from early namba nats with the gold in hand.

Mike you cut the last 3 1/2 inches off that ramp and you will be surprised how well it works too. if you add Anti trip to the front sponsons Skin the top of the sponson over onto the add on anti trip. the JAE works well in the water by itself. But the SKI ramp ( its prop plaining surfae) it the 1st thing it bumps its ass on in heat racing water & unhooks the prop.

Now you have a RR...If you are gonna do all these changes to the boat,why dont you just get a RR. JMHO. If you want to run the JAE style call the PEOPLE WHO run that style of boat,you might be surprised they might be able to help you. Boats are different weather it is a mono/rigger/sport/ scale /cat..etc. Everybody likes to set there boat up there own way,like they say...if you have a problem with your build...read the instructions.

hi stan, my boat is still a true JAE with the ski,just alittle longer and wider with a few other tweeks.also, CG is very important! rudder throw is very small and have tried a bunch of props and pipes(still testing) and the hull is very forgiving. my boat was a test bed and i am willing to share any info to help out a fellow boater get into nitro riggers,because when you get it right,they are a blast to drive and whatever you do,don't blink with this hull,it will be on top of the boueys or another boat in the blink of an eye!

 

[Greg Hahn]

you guys need to google up the JMPBA (Japan) and take a look at the boats they run. I'm pretty sure the JAE was designed using similar numbers and geometry. You'll notice that as the size and power goes up the boat gets quite a bit longer. Granted they run often in much rougher water than we do and the also run in salt water too but the boats get really long as the power goes up.Might give you some ideas.

here's three pix from a race in Japan these are all D hydros and seem to be pretty long, imagine how long a gas boat would be to achieve the same balance. jmho

 

[Michael Costanzo]

you guys need to google up the JMPBA (Japan) and take a look at the boats they run. I'm pretty sure the JAE was designed using similar numbers and geometry. You'll notice that as the size and power goes up the boat gets quite a bit longer. Granted they run often in much rougher water than we do and the also run in salt water too but the boats get really long as the power goes up.Might give you some ideas.

here's three pix from a race in Japan these are all D hydros and seem to be pretty long, imagine how long a gas boat would be to achieve the same balance. jmho

View attachment 43833View attachment 43834View attachment 43835

thanks glen,nice to see someone is on the same page.

 

[Buckshot]

you guys need to google up the JMPBA (Japan) and take a look at the boats they run. I'm pretty sure the JAE was designed using similar numbers and geometry. You'll notice that as the size and power goes up the boat gets quite a bit longer. Granted they run often in much rougher water than we do and the also run in salt water too but the boats get really long as the power goes up.Might give you some ideas.

here's three pix from a race in Japan these are all D hydros and seem to be pretty long, imagine how long a gas boat would be to achieve the same balance. jmho

View attachment 43833View attachment 43834View attachment 43835

The JAE's were originally called JAP's until they got all politically correct with the name. LOL

 

[Dave Wardle]

Am concluding theres merit in this extended hull advice on the JAE gas now.

Testing today was to include a new ski with reduced main ramp angle ... but just as an experiment a run without any ski was to be the starting point. This transformed the straight line running, attitude and speed to a competitive level, however prop/ transom bounce remains an issue during cornering with the non ski config... many strut and turn fin adjustments were tried but cornering only improved marginally . Weight was added to the rear compartment and this did reduce the skipping in corners a little (300gms) but not to a comparable standard of a Roadrunner in the same water conditions.

Next the modded ski runs...... back to being a little paddly on the sponsons although not as bad as the previous steeper ski, quite a notable decrease in straight line speed but cornering much better..... .. The ski seems to be possibly masking the prop and robbing some performance .

Next options ...... make a very narrow ski, just wide enough to cover the prop tube , really go for it and graft a few inches into the hull and run ski-less !! ... or as a boater mate suggested.... just buy a good secondhand R-Runner !!!!