JAP/JAE .12G construction

[Geraghty]

Rod,
Thanks for creating this thread. I had a slew of questions to ask this morning and was going to post them to the “.12 JAP boat plans now available” thread but when I went looking for it I found this thread and…. viola, here am. Just think, I didn’t even have to reveal my weaknesses by asking ‘all’ of my rooky questions I did say ‘all’ didn’t I? I hope so because I do have a few questions left. :huh:

1) Is it safe to assume that the sponson attachment rods are glued into place?

2) Should the inside of the sponsons have balsa blocks glued in place to support the rods or will the sponson side panels carry the entire load?

3) What about safety floatation? Is that something that needs to be worked in around all the running gear?

Thanks everyone for sharing your lessons learned. I will reciprocate when I get that far. I have to finish my Dumas Miss Unlimited build before I can start on this build. How about more build progression and completed pics?

Rod, I could not agree with you more when you say that thing about ‘building them is more fun than buying them’. Its a lot of fun putting RC and woodworking together into the same hobby.

Raymond.

Raymond,

Paying attention to flotation is always a good idea.If you build the boat per the plans there should be enough flotation to get the job done.

Usually provisions are made so the boom tubes can be replaced.This is done by glueing in tube stubs in support blocks in the sponsons.These tube stubs are then slipped inside the main boom tubes and held in place with a screw through the whole mess.Looking at the plans the boom tubes go through block in the center tub and have collars to hold them in place.

You can build the sponsons out of egg crate wood construction,plywood sheeting over foam or plywood sheeted balsa...all techniques work very well.

I think I have some construction technique photos somewhere in the colon of this computer..send me your email address,and if I can find them,I will send them to you.

Rod Geraghty email ..... [email protected]

 

[Raymond Bonenfant]

Rod,

Thanks for clearing up the boom tube issue for me. I am picking up what you are putting down B) . It all makes sense.

Yes please, if you find those construction techique photos please forward them to me. I am like a sponge trying to absorb all I can and having a ball doing it.

This website and the contrabutions of people like you is a very valuable resource supporting a non-mainsteam hobby such as this. I thank you and the webmaster for all you do. I can only hope to pass along all I learn to the next person that ventrues in looking to have some fun

Raymond

[email protected]

 

[TomMoorehouse]

Rod, what is egg crate wood construction??

 

[Geraghty]

Rod, what is egg crate wood construction??

just ribs,stringers and sheeting........

 

[Geraghty]

Rod, what is egg crate wood construction??

opps,that didn't work.......

 

[Geraghty]

Rod, what is egg crate wood construction??

opps,that didn't work.......

lets try this.....this is egg crate sponson construction

 

[LarryConrad]

An observation to share....
I bought a Hughey .150 to 3/16 flexshaft & propshaft preassembled (which I promptly proceed to cut too short :huh: :lol: ). If you chose to use Glenn Quarles Fuller's Fast Electric mini strut (not the one that kicks back).... you'll find the propshaft is quite long and even w/ the proper gapping between propshaft & flextube inside the strut and between the end of the strut and the drive dog, you'll still find need something to get the prop nut to push the prop up againt the drive dog - and Glenn suggested a piece of fuel tubing. Great solution! Thanks Glenn!

Meanwhile ordered another .150 to 3/16 flexshaft to propshaft.... this time from FunRCBoats. The propshaft from them is MUCH shorter than the Hughey one. Either can be made to work, but they ARE different.

tood why are you not using .130 ..it is much stronger than the .150 cable. i know it sounds funny but i have been told that alot by guys and proven it in my 12 boat. and you can make your own .. buy the octura setup and you can get it with the 3/16 propshaft all the other goodies all for around 11.00 and it is easy to make one..i bet larry conrad could help you out there..

terry

:huh: Terry, Leave Todd alone, he is busy trying to re-invent the wheel.

 

[dizzy dean]

joe, these motor mounts are sweeeeeet. great job for a great price. got two, maybe a twin. <_<

thanks,

tim

 

[TCHedOff]

Rod.... Cant thank you enough.... you promised an idiot proof and today that was proven - an idiot succeeded in running his little JAP today!!!!!!! :lol: :lol: :lol: :lol:

My boat has finally seen water, and every time we tossed her in, she got up on plane. This idiot cant drive yet :lol: , so I let Larry C drive it for a full tank while I snapped some shots of it.

It was SO MUCH more satisfying than my .21 rigger, which still hasnt run like it should (tho we probably spent 4-6 hrs twiddling w/it late last fall)... so for now I'm just happy to have a boat that I can toss in & RUNS!

Many things to improve.... my sponson AOA is lower than what you instructed (@3* :huh: - I JUST figured out that by using horizontal screws to join the 3 piece sponsons instead of vertical, they are allowing for quite a bit of "play"); pipe is way long (like 7 1/2"); needle is RICH; engine has only 3 tanks thru it etc etc - BUT it ran EVERY time.

This little thing's design is a real credit to you, and the testers.... again want to THANK YOU all! There are gonna be ALOT of happy boaters, if they just stick to what you showed 'em to do.

todd

 

[Geraghty]

Rod.... Cant thank you enough.... you promised an idiot proof and today that was proven - an idiot succeeded in running his little JAP today!!!!!!! :lol: :lol: :lol: :lol:
My boat has finally seen water, and every time we tossed her in, she got up on plane. This idiot cant drive yet :lol: , so I let Larry C drive it for a full tank while I snapped some shots of it.

It was SO MUCH more satisfying than my .21 rigger, which still hasnt run like it should (tho we probably spent 4-6 hrs twiddling w/it late last fall)... so for now I'm just happy to have a boat that I can toss in & RUNS!

Many things to improve.... my sponson AOA is lower than what you instructed (@3* :huh: - I JUST figured out that by using horizontal screws to join the 3 piece sponsons instead of vertical, they are allowing for quite a bit of "play"); pipe is way long (like 7 1/2"); needle is RICH; engine has only 3 tanks thru it etc etc - BUT it ran EVERY time.

This little thing's design is a real credit to you, and the testers.... again want to THANK YOU all! There are gonna be ALOT of happy boaters, if they just stick to what you showed 'em to do.

todd

Thanks for the kind words......ain't it fun when you don't have to spend all day in the retreive boat.... B)

Way to go and keep it goin'.....have some more fun and build another........post a couple of your photos of the boat running.

 

[TCHedOff]

Testing uploading pics:

http://sincitytrader.com/Uploader/files/12/TOPVIEW.JPG

Hmm.... that didnt insert the pic, but the link works...?? Oh well! In anycase you can see the overhanging edges on the sponsons & tub. I tapered the edges on the sponsons into the front tips but havent done so yet w/the tub.

Here is a sideview... (the unattached cowl is from Mark Leyde/Hydroracer's Lightning .12 boat) where you can see the "ski":

http://sincitytrader.com/Uploader/files/12/BOATSIDE.JPG

Here's the bottom side.... each flat surface on the bottom overhangs as you move rearword like shingles on a roof (does that make sense?

http://sincitytrader.com/Uploader/files/12/boatbottom.jpg

A pic of me and my son, the future boater (now you guys know who you are communicating with :lol: )!

http://sincitytrader.com/Uploader/files/12...6boatbottom.jpg

Here's a sideview of the ski & its length:

http://sincitytrader.com/Uploader/files/12/BOATSKI.JPG

This IS interesting! You can choose to use a normal strut (I bought one from Glenn Q - and it stuck up past the the top of the tub by @1/8" - I figured no problem, I'd trim it and went ahead and mounted my brass tubing for my flexshaft); but then I looked at Ron Z Jr's for the x time and noticed he doesnt use a strut at all, just brass tube to the end! So I called Rod on this and he said either way works fine but he warned if you go brass tube only, to at least double up on thickness. I opted a 3rd way, and cut off the unneeded part of the strut, and filed the nub to an angle that matches the angle of the strut (so I could achieve 0* strut angle) and then epoxied into place. Oh yeah, I used the bandsaw to cut some small notches into that angled part to give the epoxy more to bite on.

http://sincitytrader.com/Uploader/files/12/STRUTMOD.JPG

Lastly a pic of it running! Note the water behind the sponsons and that the tub is entirely out of the water! And IF you can get the pic enlarged enough, you can actually see the silver strut behind the transom (point is the propshaft is actually ABOVE the water surface; I called Rod about this and he said that is fine, I'll just be able to pull bigger props because the B/C Sholund 1445 blades arent fully in the water when in the down position/only part of the blade is submerged).

http://sincitytrader.com/Uploader/files/12/BOATRUN0.JPG

Thought I 'd go back and edit this post, now a month later.... The mod strut approach didnt work well for me... the prop was too hi out of the water. Have since pulled out the sturt piece and replaced with doubled up brass tubing for the last 2-3 inches and epoxied into place. Hope to test this and see if the prop spray comes of lower and more directed to the back now with this change.

todd

05/20/2009 UPDATE.... I've had my "doubled up brass tube only" approach break loose from the inside bottom surface of the rear ski several times now.... the epoxy just isnt holding. I finally capped off the end of the ski where the transom is w/ a 1/16" piece of ply (and a hole for the stuffing tube to pass thru. This has held up now for several tanks of fuel and some rough running (and the ski itself now has become extra floatation). Thought I p[ost this here so if someone goes the way I did, they can prevent them,selves so headache.

todd

 

[TomMoorehouse]

Can someone please tell me how wide the front and rear sponson bottoms are supposed to be? I only printed the 1st page and can't measure them.

Thanks,

Tom

got my red PVC to build a new tub.... straight this time!

 

[Geraghty]

Can someone please tell me how wide the front and rear sponson bottoms are supposed to be? I only printed the 1st page and can't measure them.
Thanks,

Tom

got my red PVC to build a new tub.... straight this time!

both sponsons and the rear ski are 1" wide......

 

[Geraghty]

Testing uploading pics:
http://sincitytrader.com/Uploader/files/12/TOPVIEW.JPG

Hmm.... that didnt insert the pic, but the link works...?? Oh well! In anycase you can see the overhanging edges on the sponsons & tub. I tapered the edges on the sponsons into the front tips but havent done so yet w/the tub.

Here is a sideview... (the unattached cowl is from Mark Leyde/Hydroracer's Lightning .12 boat) where you can see the "ski":

http://sincitytrader.com/Uploader/files/12/BOATSIDE.JPG

Here's the bottom side.... each flat surface on the bottom overhangs as you move rearword like shingles on a roof (does that make sense?

http://sincitytrader.com/Uploader/files/12/boatbottom.jpg

A pic of me and my son, the future boater (now you guys know who you are communicating with :lol: )!

http://sincitytrader.com/Uploader/files/12...6boatbottom.jpg

Here's a sideview of the ski & its length:

http://sincitytrader.com/Uploader/files/12/BOATSKI.JPG

This IS interesting! You can choose to use a normal strut (I bought one from Glenn Q - and it stuck up past the the top of the tub by @1/8" - I figured no problem, I'd trim it and went ahead and mounted my brass tubing for my flexshaft); but then I looked at Ron Z Jr's for the x time and noticed he doesnt use a strut at all, just brass tube to the end! So I called Rod on this and he said either way works fine but he warned if you go brass tube only, to at least double up on thickness. I opted a 3rd way, and cut off the unneeded part of the strut, and filed the nub to an angle that matches the angle of the strut (so I could achieve 0* strut angle) and then epoxied into place. Oh yeah, I used the bandsaw to cut some small notches into that angled part to give the epoxy more to bite on.

http://sincitytrader.com/Uploader/files/12/STRUTMOD.JPG

Lastly a pic of it running! Note the water behind the sponsons and that the tub is entirely out of the water! And IF you can get the pic enlarged enough, you can actually see the silver strut behind the transom (point is the propshaft is actually ABOVE the water surface; I called Rod about this and he said that is fine, I'll just be able to pull bigger props because the B/C Sholund 1445 blades arent fully in the water when in the down position/only part of the blade is submerged).

http://sincitytrader.com/Uploader/files/12/BOATRUN0.JPG

From what I can see,that is exactly like it should be and I would bet the boat does nothing stupid.........GREAT JOB!!!!

 

[raytam]

Tod,

Thanks for sharing. Are you ready for questions????

Is the floor of the hull 'not' suppose to be flush with the sides?

I can make sense of why you did that but is it suppose to be that way?

Would it be wrong if it was flush with the sides?

Your booms look like they have screw that run through them. Did you not glue it into place?

Thanks

Ron

 

[Geraghty]

Tod,Thanks for sharing. Is the floor of the hull 'not' suppose to be flush with the sides? I can make sense of why you did that but is it suppose to be that way? Would it be wrong if it was flush with the sides?

Thanks

Ron

I'll answer this since I am still up....

Either way will work but bottom sheeting "overhang" is the best....the "overhang" just totally eliminates any water capillary action up the sides of the sponsons,ski and tub on the launch or when the boat is running.

Study the photos Todd has posted....look how free the boat is running on the water.With flat running surfaces and overhang,the boat can be just dropped in the water and it will launch effortlessly and will be super light on the water and will do nothing stupid while running..........get the free plans and study them[read the comment block]......send me your e-mail address and I will send them to you....

Rod Geraghty ......... [email protected]

 

[Zach Davis]

Testing uploading pics:

Hmm.... that didnt insert the pic, but the link works...?? Oh well! In anycase you can see the overhanging edges on the sponsons & tub. I tapered the edges on the sponsons into the front tips but havent done so yet w/the tub.

Here is a sideview... (the unattached cowl is from Mark Leyde/Hydroracer's Lightning .12 boat) where you can see the "ski":

Here's the bottom side.... each flat surface on the bottom overhangs as you move rearword like shingles on a roof (does that make sense?

A pic of me and my son, the future boater (now you guys know who you are communicating with :lol: )!

Here's a sideview of the ski & its length:

This IS interesting! You can choose to use a normal strut (I bought one from Glenn Q - and it stuck up past the the top of the tub by @1/8" - I figured no problem, I'd trim it and went ahead and mounted my brass tubing for my flexshaft); but then I looked at Ron Z Jr's for the x time and noticed he doesnt use a strut at all, just brass tube to the end! So I called Rod on this and he said either way works fine but he warned if you go brass tube only, to at least double up on thickness. I opted a 3rd way, and cut off the unneeded part of the strut, and filed the nub to an angle that matches the angle of the strut (so I could achieve 0* strut angle) and then epoxied into place. Oh yeah, I used the bandsaw to cut some small notches into that angled part to give the epoxy more to bite on.

Lastly a pic of it running! Note the water behind the sponsons and that the tub is entirely out of the water! And IF you can get the pic enlarged enough, you can actually see the silver strut behind the transom (point is the propshaft is actually ABOVE the water surface; I called Rod about this and he said that is fine, I'll just be able to pull bigger props because the B/C Sholund 1445 blades arent fully in the water when in the down position/only part of the blade is submerged).

Sorry for all the extra post. I was trying to fix's the pictures for Todd.

Zach

 

[raytam]

Tod,Thanks for sharing. Is the floor of the hull 'not' suppose to be flush with the sides? I can make sense of why you did that but is it suppose to be that way? Would it be wrong if it was flush with the sides?

Thanks

Ron

I'll answer this since I am still up....

Either way will work but bottom sheeting "overhang" is the best....the "overhang" just totally eliminates any water capillary action up the sides of the sponsons,ski and tub on the launch or when the boat is running.

Study the photos Todd has posted....look how free the boat is running on the water.With flat running surfaces and overhang,the boat can be just dropped in the water and it will launch effortlessly and will be super light on the water and will do nothing stupid while running..........get the free plans and study them[read the comment block]......send me your e-mail address and I will send them to you....

Rod Geraghty ......... [email protected]

Thanks, Rod

I do have your plans and will take another look at them...

Next question...would adding a thin piece of ply 1/32" be too thin to attach to the bottom of all sponsons add overhang or if its flush, just leave it that way?

 

[Geraghty]

Tod,Thanks for sharing. Is the floor of the hull 'not' suppose to be flush with the sides? I can make sense of why you did that but is it suppose to be that way? Would it be wrong if it was flush with the sides?

Thanks

Ron

I'll answer this since I am still up....

Either way will work but bottom sheeting "overhang" is the best....the "overhang" just totally eliminates any water capillary action up the sides of the sponsons,ski and tub on the launch or when the boat is running.

Study the photos Todd has posted....look how free the boat is running on the water.With flat running surfaces and overhang,the boat can be just dropped in the water and it will launch effortlessly and will be super light on the water and will do nothing stupid while running..........get the free plans and study them[read the comment block]......send me your e-mail address and I will send them to you....

Rod Geraghty ......... [email protected]

Thanks, Rod

I do have your plans and will take another look at them...

Next question...would adding a thin piece of ply 1/32" be too thin to attach to the bottom of all sponsons add overhang or if its flush, just leave it that way?

Read the comments block of the plans.............

1/32 would be ok with a little fillet of filler or glue in the corners of the sponson/tub/ski sides and the overhung sheets.....Just somthing to add a bit of mechanical strength to that overhung edge of the 1/32 sheeting.....1/16" of overhang is more than enough to stop capillary action.

 

[Ron Zaker Jr]

Testing uploading pics:
http://sincitytrader.com/Uploader/files/12/TOPVIEW.JPG

Hmm.... that didnt insert the pic, but the link works...?? Oh well! In anycase you can see the overhanging edges on the sponsons & tub. I tapered the edges on the sponsons into the front tips but havent done so yet w/the tub.

Here is a sideview... (the unattached cowl is from Mark Leyde/Hydroracer's Lightning .12 boat) where you can see the "ski":

http://sincitytrader.com/Uploader/files/12/BOATSIDE.JPG

Here's the bottom side.... each flat surface on the bottom overhangs as you move rearword like shingles on a roof (does that make sense?

http://sincitytrader.com/Uploader/files/12/boatbottom.jpg

A pic of me and my son, the future boater (now you guys know who you are communicating with :lol: )!

http://sincitytrader.com/Uploader/files/12...6boatbottom.jpg

Here's a sideview of the ski & its length:

http://sincitytrader.com/Uploader/files/12/BOATSKI.JPG

This IS interesting! You can choose to use a normal strut (I bought one from Glenn Q - and it stuck up past the the top of the tub by @1/8" - I figured no problem, I'd trim it and went ahead and mounted my brass tubing for my flexshaft); but then I looked at Ron Z Jr's for the x time and noticed he doesnt use a strut at all, just brass tube to the end! So I called Rod on this and he said either way works fine but he warned if you go brass tube only, to at least double up on thickness. I opted a 3rd way, and cut off the unneeded part of the strut, and filed the nub to an angle that matches the angle of the strut (so I could achieve 0* strut angle) and then epoxied into place. Oh yeah, I used the bandsaw to cut some small notches into that angled part to give the epoxy more to bite on.

http://sincitytrader.com/Uploader/files/12/STRUTMOD.JPG

Lastly a pic of it running! Note the water behind the sponsons and that the tub is entirely out of the water! And IF you can get the pic enlarged enough, you can actually see the silver strut behind the transom (point is the propshaft is actually ABOVE the water surface; I called Rod about this and he said that is fine, I'll just be able to pull bigger props because the B/C Sholund 1445 blades arent fully in the water when in the down position/only part of the blade is submerged).

http://sincitytrader.com/Uploader/files/12/BOATRUN0.JPG

Ted,

My boat DOES A HAVE STRUT. Maybe the pic is not clear?