Help me build a Sniper 45"

[RaceMechaniX]

Mine came with rails installed although I ended up extending the front portion to pick-up the motor mounts. 6" offset rudder.

[kevinpratt823]

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Did a little each day this week. Glassed in the transom with combo mat/cloth then patched in the edges with scraps of mat, glassed the hatch with mat, laid in the carbon kevlar, and built up the bridge over the top in front of the hatch with a layer of mat/cloth combo that rolls all the way down to the beginning of the V, really stiffened the area up and gave a ton of support. The rails are just for testing and fitting, I will match what I have to 1/4 birch lam plywood and install those next....... Also, as the carbon shifted and only made it up past the seam on one side, I ran a strip of cloth down the seam on the other side.

[keithbradley]

I use isopropyl alcohol to thin my epoxy. It was recommend by one of my supplier tech adviser as a good way to thin epoxy for a thinner viscosity.

If used for structural purposes, you shouldn't add alcohol to epoxy resin. It will significantly diminish the strength of the epoxy.

OP, are you using this epoxy resin in cool temperatures? Z-poxy finishing resin isn't that thick (for small bottle type epoxy) and certainly shouldn't be giving you issues with wetting out cloth. Make sure you are not in a cold environment when using the resin, and heat each bottle to around 100F-105F before mixing (can be done by placing bottles in warm water). Heat will thin the mixture substantially but also causes it to cure faster so beware of a shorter pot life.

[kevinpratt823]

If used for structural purposes, you shouldn't add alcohol to epoxy resin. It will significantly diminish the strength of the epoxy.

OP, are you using this epoxy resin in cool temperatures? Z-poxy finishing resin isn't that thick (for small bottle type epoxy) and certainly shouldn't be giving you issues with wetting out cloth. Make sure you are not in a cold environment when using the resin, and heat each bottle to around 100F-105F before mixing (can be done by placing bottles in warm water). Heat will thin the mixture substantially but also causes it to cure faster so beware of a shorter pot life.

I only used the Z-Poxy in the hatch, then I bought some fiberglass resin from West marine(not the west system) that uses the methyl ethyl keytone hardener, and it mixes much thinner and easier to work with. The temp is prob low 60's in the work area. I think the problem with the Z-Poxy seemed worse because I was using it on mat, which starts to come apart while dabbing and shaping it into the hatch as the mix begins to get tacky. All went well with the new resin.

[kevinpratt823]

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Made up my rails and drilled them for both center and front motor locations(I realize I'll prob never find the holes again after I lay in the carbon, and will prob be drilling again in a more revised location), the tall part runs all the way up in case I decide to mount the motor forward. Mounted them up with the motor, shimmed out with 2 good sized washers on either side to allow for the 2nd inlay of carbon kevlar, plus a little side to side shimming to locate the motor where I want it to possibly offset it a fraction to the right, as my strut will be exititng a touch right of center. I epoxied them in, then I laid in what I had left of the carbon kevlar at a 45 deg angle(more strength)to the first inlay.
I was told I would not be able to wrap over the rails, so at the last minute I decided I had to try it(hopefully didn't screw myself). I can always grind down the top and/or lay on some glass in the outer seams(the inner should be pretty solid. The one mistake I made without realizing it, is that apparently the carbon kevlar's edges are bound with scotch tape to prevent unraveling, and I didn't remove it along one edge. Hopefully enough resin soaked in from under to bond it down.

Carbon fiber tube is on the way for a flooded stuffing tube setup.......

Feedback????? How am I doing???

[srislash]

Well,I think it looks good Kevin,mind you I have not attempted this yet.My DF45 is on end waiting for inspiration.

[kevinpratt823]

Well,I think it looks good Kevin,mind you I have not attempted this yet.My DF45 is on end waiting for inspiration.

Thanks Slash, I hope I can help inspire you with my build

[srislash]

Thanks Slash, I hope I can help inspire you with my build

I think I'm going twin with mine Kevin.I have two other large hulls for singles. I'm hoping for a light twin from this hull.But definitely paying attention to you'rs.

[kevinpratt823]

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OK guys, I could really use some input from those of you in the know. I got a CF tube on Ebay for $18 shipped, they are overstock cuts a little over 12" and just under 1" OD, can't post the link per forum rules, but if you want info PM me. I made my hole for he tube as low as possible, and about 1/4" off center, and laid out my hardware as to what I think will work. The 6" rudder bracket seems awfully long for this setup. I think I'm keeping the motor forward to leave me flexibility with batt placement, lmk what you think about what I've got thus far, and if I should do anything differently. The plywood is just temporary until my CF sheets show up from Kintec.
Is this Hydra Ice 200HV(stlii contemplating how/where to mount it) going to handle this Castle 2028 pushing this boat on 10s?
Thanks.

[forescott]

I dont understand the big tube. What is its purpose, and what keeps water from coming inside the hull?

[kevinpratt823]

I dont understand the big tube. What is its purpose, and what keeps water from coming inside the hull?

It is a "flooded stuffing tube" setup. The front will be secured and supported a bit off the floor, and closed off around the stuffing tube. This setup will allow some verticle adjustment of the strut because it allows the stuffing tube to move up and down without also changing the prop shaft angle as it would with a stinger. My Impulse 31 was like this, and I liked the tuneability. RaceMechanix posted a link to his build like this(1st page) from last year and there is some good explanation about it. His is one of the builds I am getting ideas from.

[forescott]

aaaaah, ok.

[lenny]

The CG would be a lot lower if you put the cells inside the rails and against the tube and bottom of the hull.
And you could flip the servo around and mount it in the rail, And that would give more room for cells to move back to,
The 6" rudder bracket seems awfully long for this setup.
The longer it is the more torque and stress it will place on the transom to.

[kevinpratt823]

The CG would be a lot lower if you put the cells inside the rails and against the tube and bottom of the hull.
And you could flip the servo around and mount it in the rail, And that would give more room for cells to move back to,
The 6" rudder bracket seems awfully long for this setup.
The longer it is the more torque and stress it will place on the transom to.

Thanks. I actually test fitted things in the way you described as well, I will definitely consider that also. The battery tray idea would be removeable in case I decide to go the route you described.
I got the 6" rudder mount based on RaceMechanix build, but I think I will order a 4-5" to try out as well. Also thinking of blocking the strut mount off the transom a bit, as it seems pretty close.

[Heaving Earth]

Looks like trim tab brackets are upside down.
Flooded tube looks good

[kevinpratt823]

Looks like trim tab brackets are upside down.
Flooded tube looks good

Lol, you are correct, I just stuck them on for the pic, didn't even realize it.

[Heaving Earth]

Looks like a nice boat you're doing

[RaceMechaniX]

Kevin,

Before you glass the tube in, mount the motor, T-bar and bend the stuffing tube the way you want it. Use the next larger size brass tube to make a "pass through" where the piece of tube will be epoxied in place. This will allow you to remove the 5/16 or 11/32 stuffing tube should it fail. Position the motor side of the flooded stuffing tube so there is an 1/8" of gap on the top between the ID of the carbon tube and OD of the brass "pass through" piece. This will allow epoxy to get all the way around and provide more structural support and a better seal. It ends up looking like the carbon tube has a slight downward tilt towards the transom when all said and done.

TG

[kevinpratt823]

Kevin,

Before you glass the tube in, mount the motor, T-bar and bend the stuffing tube the way you want it. Use the next larger size brass tube to make a "pass through" where the piece of tube will be epoxied in place. This will allow you to remove the 5/16 or 11/32 stuffing tube should it fail. Position the motor side of the flooded stuffing tube so there is an 1/8" of gap on the top between the ID of the carbon tube and OD of the brass "pass through" piece. This will allow epoxy to get all the way around and provide more structural support and a better seal. It ends up looking like the carbon tube has a slight downward tilt towards the transom when all said and done.

TG

Thanks Tyler, I really appreciate you following this thread. Glassing the tube in will definitely be the last step, after I have the motor/T-bar set, and tube shaped, and I will be sleeving the brass like you said. I am thinking of what to fill the end of the flooded tube in with, I would like to close it off with some sort of plug, or at least a couple CF disks that would be drilled out in the center for the brass and epoxied into the end. Did you just use epoxy alone to seal the end off?

[srislash]

I've been contemplating a rubber grommet to seal the front of the flood tube.I'm paying attention here for a couple builds Kevin.I have a pursuit that I am putting the flood tube in as well and am thinking of the offset like you have done.

Now on another note,this is how my 35"DF is setup with a 1717 under the ESC.The 2 batteries beside the motor make it carve corners like crazy.When I got the boat they were down the sides and it hopped and chined all over.
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[kevinpratt823]

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Got the motor/T-bar installed, started on the driveline. Played around with a few ideas for batt placement and servo location, the three layous in the pic all give me roughly 33% cog with room for adjustment.

Thanks for the input Slash. With the little experience I have had with mono's so far(Impulse, Cyberstorm) I would definitely believe you. It would seem that if ALL the wieght is in the centerline, or on the outsides, it is too easy to throw off balance. To me it seems to work best when the weight is distributed a bit. Same seems true for front to back, i.e. If your weight is too focused near the COG, it makes it rock a lot more using the COG as a pivot point, and possibly letting the bow too far down at the wrong time and causing the boat to dissapear suddenly.

Of course I could be way off with those observations though.

As far as sealing the flooded tube, with this boat I am worried the driveline may get too hot for a rubber grommet/stopper, still pondering....

[Punisher 67]

Kevin where did you get the adjustable T-bar

[srislash]

With the little experience I have had with mono's so far(Impulse, Cyberstorm) I would definitely believe you. It would seem that if ALL the wieght is in the centerline, or on the outsides, it is too easy to throw off balance. To me it seems to work best when the weight is distributed a bit. Same seems true for front to back, i.e. If your weight is too focused near the COG, it makes it rock a lot more using the COG as a pivot point, and possibly letting the bow too far down at the wrong time and causing the boat to dissapear suddenly.

Of course I could be way off with those observations though.

As far as sealing the flooded tube, with this boat I am worried the driveline may get too hot for a rubber grommet/stopper, still pondering....

Mine was really P'ing me off as I am used to cats(first mono setup).I fought with the weight/balance for awhile then finally a small amount of trim tab and wala...

[RaceMechaniX]

Kevin,

To seal off the flooded stuffing tube I used a round disk with a hole offset that the stuffing passed through. I tacked the disk to the end of the carbon tube with some CA. Tipping the boat vertical with the nose down and supported I used a syringe with epoxy and a straw to place the epoxy down the tube without letting it dribble on the brass or carbon tube. Just make sure you CA around the disk completely or you may end up with a puddle of epoxy on your motor. Let the epoxy cure overnight and you are ready.

TG

[kevinpratt823]

Kevin where did you get the adjustable T-bar

Peter, I actually scooped it up on the Swap forum here, but it is made by Arrow Shark, and you should be able to find it on Ebay or otherwise. It has a cool oiler can on top too that directs it right to the shaft if you drill a small hole. It won't quite clamp down on an 11/32 tube though, probably be using some teflon tape or silicone, tried heat shrink, but it was too big.

Thanks Tyler, I think I'm going with a similar idea on sealing the tube. That sounds pretty tricky, I was thinking of putting epoxy in from the motor end, and standing the boat on the transome, but your way would definitely give a better finished look.

[Punisher 67]

Thanks for the reply Kevin - I can actualy machine my own but its always nice to veiw other designs .

[lenny]

Hey Peter,
Hears a link to it.
http://search.yahoo.com/r/_ylt=A0oG7....com/T-bar.php

Thanks for the reply Kevin - I can actualy machine my own but its always nice to veiw other designs .

[lenny]

Hey Kevin,
How about a small peace of fuel tubing to go over the flex tubing to make a good tight fit on it,
Just add some lube to make it easier to get it to go over it.

[kevinpratt823]

Hey Kevin,
How about a small peace of fuel tubing to go over the flex tubing to make a good tight fit on it,
Just add some lube to make it easier to get it to go over it.

It is only a tiny fraction of a gap, but enough that the tube would still rotate. It wasn't even enough of a gap to fit the brass tube through with a short piece of heat shrink on it, so fuel tube definitely won't fit, I think I'll try the heat shrink again, with a little more finess and some lube, I don't think it would even be enough to fit an exta 3/8" brass tube sleeve over the 11/32, (which is a sleeve over the full length of 5/16").

[kevinpratt823]

I am not sure what you have going on there,
But I think you just need the T bar to be a snug fit to the tube.
Like if you back off on the bolt that holds the tube and spread it open some,
Like it was when new.
Then see how much room you have to work with around the tube.

It is brand new. The block is very rigid, and it doesn't just spread open when you loosen the bolt(tried prying with screwdriver). There is very little give in the clamp to open/close it. I'll get something to work, not a big deal, I just got into that part yesterday and haven't spent much time on it yet. The T-bar needs to be a snug enough fit to seal it off all the way around because of the built in oiler hole/reservoir, I'll post some better pics when I get working on it in a few.....