OM21 build

[saleens7]

i took out the shaft and rolled it..its perfectly strait...ive put the batt as forward as possible, and it still bounces...ill try to see if i cant push it even more forward...i dont think il be able to use trim tabs anyway, there just isnt enough room.....i dont see how it just suddenly started to vibrate....same motor, same mounting position, same everything, yet only now does it vibrate...

i guess a brace would be good to help support the stuffing tube....epoxy is drying on one as i type

[ozboater]

if i m not mistaken i m pretty sure that you re not supposed to use epoxy on ABS... i think CA glue is the stuff to use - i could be wrong tho'... my mate recently built an OM21 and i think he mentioned that randy n suggested CA...

[Doug Smock]

Hey saleens7,
I just went back and reviewed your pics. How much shaft do you have sticking out beyond the stern tube at the transom??

Doug

[saleens7]

Hey saleens7,
I just went back and reviewed your pics. How much shaft do you have sticking out beyond the stern tube at the transom??

Doug

a tad more than 2 1/2"...

[saleens7]

if i m not mistaken i m pretty sure that you re not supposed to use epoxy on ABS... i think CA glue is the stuff to use - i could be wrong tho'... my mate recently built an OM21 and i think he mentioned that randy n suggested CA...

you can use epoxy, it just wont hold as well sicne the surface of ABS is smooth...but i sanded the hull where i would use epoxy, that way it will hold better....

[Doug Smock]

a tad more than 2 1/2"...

I would be willing to bet that, that is the source of the vibration. You need support at the end of the shaft @ the prop.
Also what do you mean you don't have room for tabs.

Doug

[saleens7]

on the side with the rudder, i done have room for tabs...the rudder is too low to the bottom of the hull i cant fit the trim tabs under it....i could mount them further to the side, but its too far out that they will be out of the water when the hull is on plane....

[Doug Smock]

on the side with the rudder, i done have room for tabs...the rudder is too low to the bottom of the hull i cant fit the trim tabs under it....i could mount them further to the side, but its too far out that they will be out of the water when the hull is on plane....

Can you post a pic?
Doug

[saleens7]

here they are...

[Doug Smock]

Yeah that rudder eats that transom alive.
You could get creative with some thin aluminum and make some tabs. If you have to tuck the right one up under the rudder and shim the top to even things up.
You can make it happen!!

Doug

[Doug Smock]

Make something like this.

[saleens7]

looks like ill be makign a trip to the hardware store soon....to pick up some brass tubing and some aluminum sheet metal...ive already made a strut from an old rudder mount and some of the extra ABS from the hull (the stuff you cut out from the deck, under where the hatch goes, that way you can get inside the hull when you take the hatch off...all i need to do is find some brass tube the same size that is the stuffing tube now and JB weld it to the mount...ill see if i cant make some small trim tabs from aluminum sheet metal...

[Ctonez]

actually, i hve found electrical tape to leave a sticky, black residue...id does all the time when i use it to cover exposed wires and when i used it to seal up some of those batt packs piranha2 gave me...

I've been using the colored vinyl tape from home depot...maybe it's not really "electrical" tape, I dunno...no residue though...I know the residue you're talking about it IS goopy and gross, but this stuff comes off clean and seals well.
I still prefer more traditional hatch tape though.

[saleens7]

ill eventually buy hatch tape, but ill have to stick with electrical tape for now...i really need a new prop though....this little 31mm isnt big enough....it takes like 15-20 feet before it gets on plane and it only does like 15mph...with the old prop i swear it was just hitting 20 on a fresh batt....

[saleens7]

well...turns out the only prop i have now is broken....one of the blades are chipped....(if you look at the pics i posted of the rudder a couplr posts up you can see the crack on the prop....so now i have to get a new prop to run it....

still though i really like this hull...i think i might buy another and set it up with a brushless system....