JAE Rear Ski

[Blackout]

I got thinking about "stand still" flotation from another thread. Has anyone thought about or added foam in the forward part of their JAE rear ski? This would increase flotation a little if both front sponsons are sheared off from an accident. I suppose you could just seal off part of the ski with a piece of 1/8" thick lite-ply and not add foam. This would work as long as there isn't a leak created from damage to the ski. Any thoughts?

Thanks.

 

[Ron Zaker Jr]

I got thinking about "stand still" flotation from another thread. Has anyone thought about or added foam in the forward part of their JAE rear ski? This would increase flotation a little if both front sponsons are sheared off from an accident. I suppose you could just seal off part of the ski with a piece of 1/8" thick lite-ply and not add foam. This would work as long as there isn't a leak created from damage to the ski. Any thoughts?

Thanks.

Possible heat issue on the driveline.

 

[Don Ferrette]

I got thinking about "stand still" flotation from another thread. Has anyone thought about or added foam in the forward part of their JAE rear ski? This would increase flotation a little if both front sponsons are sheared off from an accident. I suppose you could just seal off part of the ski with a piece of 1/8" thick lite-ply and not add foam. This would work as long as there isn't a leak created from damage to the ski. Any thoughts?

Thanks.

Possible heat issue on the driveline.

Eagle SG and SGX's have used foam filled center skis for years without issue. Once the ski was made the channel was cut out to fit fairly snugly around the shaft tube. If I recall correctly the SGX21 center ski is all foam with a single piece of ply on the bottom ride surface.

 

[Alexander King]

I too was thinking of doing the same thing with mine.. it shouldnt cause a issue .. Im not going the whole length of the ski... just halfway . is there that much friction in the stuffing box to cause High heat and the foam to insulate it? I figured that halfway would allow for cooling and adjustment If needed....

 

[Don Ferrette]

I too was thinking of doing the same thing with mine.. it shouldnt cause a issue .. Im not going the whole length of the ski... just halfway . is there that much friction in the stuffing box to cause High heat and the foam to insulate it? I figured that halfway would allow for cooling and adjustment If needed....

If there's that much friction to get it hot enough to worry about the foam then I'd say a better shaft grease is in order.

 

[James Croskrey]

I was trying to figure something out all Summer for my JAP and was palnning on foaming the rear ski on the JAE that's in build right now. The rear ski was the only real option I could come up with without adding drag to the rigger. I'm going to do it to both riggers and to my .21 JAE when it gets here.

 

[tmunn]

Why would you even bother with adding foam ???

If you break both boom tubes you would also have to damage the radio box so the air would leak out and or water in .It would be much easier add peices of pool noodle or styrofoam to the inside of the radio box would it not...

 

[Alexander King]

Why would you even bother with adding foam ???

If you break both boom tubes you would also have to damage the radio box so the air would leak out and or water in .It would be much easier add peices of pool noodle or styrofoam to the inside of the radio box would it not...

Room! Not much in the 12 and its just easier to place it in the sky..

Yeah If the stuffing box is that hot there is some issues I think!!! Don

 

[Blackout]

Why would you even bother with adding foam ???

If you break both boom tubes you would also have to damage the radio box so the air would leak out and or water in .It would be much easier add peices of pool noodle or styrofoam to the inside of the radio box would it not...

Having foam in the rear ski would still help keep the tub from sinking. As assembled per instructions, the ski does not add any flotation.

 

[tmunn]

You would have enough room in a jae 12 box to put enough pool noodle peices in the box to float it , I am pretty sure .I am building one and have the recommended servo and 2 mini servo's one for the throttle and one for the 3rd channel and i think i can find enough room for floatation to float the hull.

Perhaps i am wrong

If the foam in the ski works for you then cool..have at it..

I just looked in my box and I know i can get more in there than the ski could ever hold.

Anyway...more than one way to skin a cat..

Terry

 

[SayMikey]

Wood floats. Shear the sponsons and it should float nose up. The whole front is foam. We are talking about a small engine with little added weight......

 

[John Knight]

Guys,

You are taking the wrong outlook at this situation. I have run riggers for 18 years, from 20's to 90's and NEVER had a complete wreck and lost everything. Maybe luck but maybe not. It is quite rare to break off BOTH sponsons and break open the radio box too. Have wrecked off one, torn up both, had the radio box opened but left the sponsons attached. What you are talking about is the perfect storm and all you would need is a minnow net to collect up the pieces. Remember, the sponsons are foam, the tub nose internals are foam and the remainder of the boat is wood except for the hardware and radio gear. The weakest part of a rigger are the boom tubes and they generally crack but usually still remain in place.

Adding in a little bit of foam in the skid will make little difference in a major wreck. BTW, Andy Brown told me that the Eagles center skid sponson was made of kelgecell structural foam framed with thin ply. Adding foam in the radio box is of little value too. It may get in the way of the radio linkages, cause a bind and result in a wreck. Think it all the way through. Build it well and concentrate on the radio box, it is a air cell if it remains intact. The boat will always float if is not opened.

 

[TCHedOff]

For what it is worth, I ended up (after 1/2 the season) sealing the rear part of the ski just under the transom with a vertical former of ply - it was airtight - mainly because I made the mistake of not using a strut and epoxy wouldnt keep the stuffing tube down onto the ski. It did help with flotation somewhat and reduced the "Hey I cant see your boat!".... But I'm never gonna use that (algea) green color again either. LMAO!

 

[tnrcboatracer]

My rule of thumb is 1 sponson removed and the radio box watered. I will build the 21 and 45 versions, but no plans for a 12 size at this time. I also plan to use foam cored CF/Kevlar tub sides and bulkheads.

I have had the pleasure of wading for John Brown's 45 SGX and an infamous bouy 1 incident at the 97 or 99 Internats at Huntsville. The tub was snapped in two at the rear boom tube and sank. I don't think any amount of flotation would have helped in that wreck.

 

[moparbarn]

on the .21 jae, the entire nose is foam filled, so no flotation issue there.

 

[Ron Olson]

Keep in mind that a sealed radio box will be like floatation. Adding any floatation in the ski is like asking a pool noodle to float a 400# person. On the JAE .21 you could add some foam around the fuel tank to give you more than what you'd get inside the ski, it would help to secure the tank also.

 

[Don Ferrette]

Keep in mind that a sealed radio box will be like floatation. Adding any floatation in the ski is like asking a pool noodle to float a 400# person. On the JAE .21 you could add some foam around the fuel tank to give you more than what you'd get inside the ski, it would help to secure the tank also.

One thing to think about in regards to the center ski besides what additional floatation properties might be gained is that a ski built around a foam core is stronger than just 3 sides of ply without virtually any real weight gain. Just my 1.3 cents (adjusted for current economical conditions).

 

[Blackout]

Keep in mind that a sealed radio box will be like floatation. Adding any floatation in the ski is like asking a pool noodle to float a 400# person. On the JAE .21 you could add some foam around the fuel tank to give you more than what you'd get inside the ski, it would help to secure the tank also.

One thing to think about in regards to the center ski besides what additional floatation properties might be gained is that a ski built around a foam core is stronger than just 3 sides of ply without virtually any real weight gain. Just my 1.3 cents (adjusted for current economical conditions).

Don, Good point.

I think I will add a foam core for strength and for raising the rear of the boat a bit higher in the water incase the boat goes dead in the middle of a race. Like mentioned in an earlier post, dead boat visibility would be a little better. Adding foam to the radio box or fuel tank area would not help increase dead boat visibility.

 

[John Knight]

Keep in mind that a sealed radio box will be like floatation. Adding any floatation in the ski is like asking a pool noodle to float a 400# person. On the JAE .21 you could add some foam around the fuel tank to give you more than what you'd get inside the ski, it would help to secure the tank also.

One thing to think about in regards to the center ski besides what additional floatation properties might be gained is that a ski built around a foam core is stronger than just 3 sides of ply without virtually any real weight gain. Just my 1.3 cents (adjusted for current economical conditions).

Don, Good point.

I think I will add a foam core for strength and for raising the rear of the boat a bit higher in the water incase the boat goes dead in the middle of a race. Like mentioned in an earlier post, dead boat visibility would be a little better. Adding foam to the radio box or fuel tank area would not help increase dead boat visibility.

If you want better dead boat visibility, paint the boat BRIGHT color(s) and that will help. Forget the wood or black/dark colors, they are very hard to see. Besides a rigger is hard to see first of all and 20 is very small, especially in the turns and on the back straights. Go bright, day glo colors and you will be better off.

 

[tmunn]

I know the pool noodle in the radio box would work for a fact and if you use a shot of goop they are not going anywhere..been there done that I use one to house my rx in my 21 hawk and it has not budged after more than one cut off bouy but I am with Mr Knight on this one paint em bright so everyone can see em..

over and out....