Puma (seaducer copy) Prop Walk

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catman

Active Member
Joined
May 22, 2004
Messages
30
I have a copy of a seaducer 44 inch mono with a os .61 vrm, it goes well except when you hit full throttle, it turns right by itslelf , it takes quite a bit of left rudder input to keep it straight, thus causing drag and costing speed, it also leans over to the right .

the hull has a hook in to keep the bow down in the chop, aparently the person who made the hull seems to have a bit more hook than normal in all of their hulls, the person who had the hull before me had started bogging a little of the hook out, im thinking of sanding a little bog out of the right side to reinstate a bit of the hook (hopefully that will lift the right side back up and get it running straight, im running direct surface drive on a x455/3 the prop is only about 2 inches off the transom i have an octura strut with an offset rudder, i have no trim tabs at this stage.

Any hints , tips, advice would be real helpfull

Cheers
 
Maybe the boat has not been built according to the instructions because the Puma should have the shaft offset to the right by 2 to 4mm for a 10 to 11cc engine. This is to compensate for propwalk/torque. Also make sure the prop is very sharp. Doing this should cure the problem you appear to have. :)

Dave

Heres a link to a pic of my own Puma with Geared CMB45 and X4557/3. As you can see it has no filler or trim tabs but is built to the instructions with some shaft offset. http://www.prestwich.ndirect.co.uk/PUMA.h1.jpg
 
Last edited by a moderator:
Catman

I've run the puma with CMB 80, no problems with propwalk at all. Built according to the instructions with a sharpened an balanced X460 or X462 prop.

Brian Mahoney
 
Thanks for your replies guys, i didnt build the boat unfortunately, the driveline looks to be aligned to the center, My prop however does need a lot of sharpening, i was in a hurry to get it into the water so only gave it a rough sharpen, i will spend a few hours tidying it up and see if that makes a difference. also someone suggested i might try a small lead weight on the left side of the boat to counteract the roll.

How Fast does the puma go with a Cmb .80, it must be ballistic
 
i forgot to mention the boat rolls over onto the right side as well as turning right
 
Catman

Start with sharpening and balancing the prop.

Never run a surface drive boat without fist sharpening and balancing the prop. An out of balance prop will shake the boat to pieces, and can be dangerous.

A prop that is not sharp will cause all the problems you have mentioned. The blade should be sharp enough that you need to be carefull when hadling to avoid cutting your fingers.

Have you sharpened and balanced props before?

The puma is quite quick with a CMB 80, probably mid to upper 50s on 10% nitro.

Brian Mahoney
 
Hi Brian and Dave, Thanks for the information so far. Do either of you know where i can download a video of a puma going 50mph ? I first thought the shaft had been offset the corect way, it is about 4mm to the left, also the previous owner has sanded a flat surface on the keel near the back of the boat it is about 10 inches long, im presuming its not meant to be there.

I had balanced this prop but hadn't finished sharpening it as i was too anxious to get the boat in the water, im actually sharpening it right now and will balance it again. :D

even with the torque roll the boat handles nicely and id like to get another one with a different engine combination to race in a different class

Thanks again for the advice :D
 
If your strut and shaft are off set to the left what you'll need to do is take it out fill the hole and drill a new one to the right not the left. The slight off set on the right side won't allow that boat to run proparly.

Also, if you take a sharp, straight ruler and lay it on both sides of the bottom is it completely flat?? Or are there waves?? A couple things you can do would be break off the shinny glossy finish left by the clear coat to prevent drag, or use filler to make the surface FLAT to gain speed.
 
catman

The Puma is molded with a flat section (ride pad).

When you say the strut is offset to the left is this looking froom the back of the boat?

Looking from the back of the boat I would expect the strut to be 4mm to the right of center.

Brian
 
yes, when looking from the back the strut is to the left , looks like im going to have to do a bit of work, the stuffing tube is silastic'ed into the bottom of the hull, any hints on how to remove it ?

The ride pad surface is flat. i have sharpened the prop to almost razor sharp, i will give it another run before i remove the stuffing tube
 
Dave, Does your boat have the shaft off to the left being gear drive or does your motor run in reverse rotation to allow normal props and its still be on the right, im just wondering if possibly the person who owned it before me had it geardrive and ran right hand props, i will ask him

Thanks again everybody :D
 
No no no. Its been built incorrectly. Geardrive makes no difference, it would still use normal LH props and no one would run RH props unless they needed a brain transplant. There is no solution other than to bite the bullet and move the shaft. Its not such a difficult thing, about an hours work at the outside I would guess.

Dave
 
Thanks Dave i will move the shaft this weekend, i just got back from the pond, with the sharper prop it is no where near as bad and only takes a small amount of left rudder to keep it straight, it still goes / handles real well even with a bit of a roll on
 
Catman you are probably confused at this time, maybe yes, maybe no. :rolleyes: What they mean is to drill the shaft hole in the transom 2 to 4mm to the right of center, not angle the strut to the right. This will move the strut off center to the right which will pick up the right side of the boat, help it run level and straight. If it still pulls to the right, angle the strut to the left 2 to 3 degrees by adding a wedge under the strut bracket. ;)
 
i fully understand ill have to redrill the stuffing tube at 4mm left of the keel, im going to do that tonight, i just have to get some neutral cure sikaflex to restick the sucker back in

Thats hard case about the copy of the puma on ebay, i wonder if it actually goes any good
 
Interested to see why the Puma was described as a Seaducer copy... Boats can look similar and have similar features - design parameters but not be copies??? How many riggers use the same basic layout????

Not going to delve into that argument but only expecting 50mph??? Have a Seaducer (original) with a stock A90 that has been clocked at over 60mph in circuit trim. 50 should be no big deal???

EMS Racing 3 Seaducers and contemplating number 4
 
odd, when i went to hong kong last year, i didnt see any gas or nitro boats, not even an electric boat, i only saw cars and planes.
 

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