sharpshooter... Sports Hydro.

[785boats]

Well, Petes' ('Shooter' on these forums) kit arrived down here in Aussie land, & with the clear & concise instructions on a pdf file, I was able to stick a few bits of ply together & end up with a very nice frame for a sports hydro. No worries at all.
The whole thing went together extremely well. So fast in fact that I forgot to take any pics of the initial stages.
But the instructions are so much more informative than anything I could have shown anyway.

As with most of these kits the whole frame is dry assembled & everything is tacked into place with medium CA glue, keeping everything straight & true with weights & clamps.

The first pic shows the basic frame built, & I was just gluing in the 1/8" x 1/8" stringers.

The next one shows the air break panel added & an extra 3/16" x 3/16" stringer that I always add through the centre of the ride pad on all the hydros I build. just for a bit of extra strength.

The next two show some extra wood that I always add to the tips of the sponsons to add a bit of extra 'gluage' area for the skins. It may not be required, but it is in all my wooden hydros. And it helps make the tips nice & strong.

[785boats]

Then it was time to add the side skins on the sponsons.
I like to prebend the ply around a 4" pole in my garage to allow for easy installation while gluing. The clamps don't have to deal with too much pressure while holding them in place.
The first pic shows the pole & the skin being bent.
The next pic shows the skins bent & ready for installation. Again just dry fitted with clamps & CA wicked along all the joins. As shown in the third pic.
Note that in these pictures the framing jig (supplied) is always clamped between the sponsons to keep everything nice & square.

[785boats]

The next evening I trimmed & sanded the edges of the side skins & added the ride plates. But here I like to use epoxy to hold them on. Just feels stronger to me at these points. I feel that it seals all the edges a bit better.
Again, it is just something that I've always done with all the other wooden hydros I've built.

The first pic shows the ride pad being held in place with a few weights & clamps.

The next pic shows the front sponson pads with the usual weights & clamps. Again, they needed a bit of pre-bending on the pole to make them fit nicely.

The last pic shows the sponson bottoms all ready for final trimming & sanding.
That where she sits at the moment.

[ray schrauwen]

Subbed. You are almost done! Nice so far. It's nice to follow someone else before I start mine.

[785boats]

Thanks Ray.
When are you going to start yours?
The instructions make the build very easy.
In hindsight, the only thing I would change, would be to spot tack the framing jig between the sponsons with some medium CA glue instead of clamping it.
The clamps kept getting in the way.

[Shooter]

Wow. Nice job. I like the extra wood in the sponson tips, and tacking the jig in is a great idea.

[785boats]

Thanks Pete.
I just use hard balsa in the tips. It is really very strong once it has soaked up a bit of CA. And it's easy to shape. It just gives me a bit more confidence that the skins won't separate at the tips when I plough into a buoy, or something, at full noise.

[785boats]

Well I've had a nice easy, but productive Sunday morning here.
Epoxied on the floor pan.
The floor pan is one piece, but because the floor changes angle at the main bulkhead that forms the rear of the sponsons, I glued the rear part of the pan first & weighted it down on the bench. (see pic). When that had set, I smeared epoxy onto the frames in the front part, turned the boat over & weighted the front part of the pan down.

Next I made the turn fin backing block from some 6mm Aluminium plate. Also a 3mm Aluminium plate doubler for the transom. And then the 3mm motor mount. See the second pic.

The whole of the insides were then given an epoxy sealer. When that dries I'll add the foam blocks.

The last thing I've done was to join the two top deck pieces. They have a sawtooth join that needs to be epoxied together. As did the sides of the hull too.
Following the instructions I just layered them on top of each other with some grease proof cooking paper above, below, & between them. Then clamped them to the bench. Too easy.
This hull is a dream to build.

[785boats]

While I was watching the last round of the V8 Supercars this afternoon, I added the foam blocks down the hull & poured the 2 part Urethane foam in the sponsons. That's another thing I do with all my wooden hydros.
Then the excess was cut away & the top all sanded smooth ready for the top skins.

[Shooter]

You are absolutely flying on this build! The foam looks great. I have to learn how to do that!

[785boats]

The foam really makes the sponsons nice & rigid.
Another thing I like to do is add a piece of 0.5mm ply on the transom & the heels of the sponsons to cover & seal all the ends of the stringers & chine pieces. A good smear of epoxy here to seal all the edges too.
Here's a before & after shot.

[ray schrauwen]

I'm waiting on some epoxy to arrive. When it comes I will start this fine toy boat.

[longballlumber]

I am curious...

When you use the foam to fill the sponson sections with foam, do you recess the foam just below the framework? Or do you sand flush with the structural components? Let me explain the reason for my question. I want to understand if when gluing the deck on the boat your relying on the foam for structural integrity or if your using the actual bulkhead frame work as the structure?

Later,
Ball

[Heath M]

Looking good Paul, EA or EB?

[ray schrauwen]

When I did my Whip 40, foam and bulheads were sanded even so I could glue the skin to both of them. I use cut foam not poured. I'll do same with this.

[longballlumber]

When I did my Whip 40, foam and bulheads were sanded even so I could glue the skin to both of them. I use cut foam not poured. I'll do same with this.

So are you relying on the foam or the sponson bulkheads to provide the best structure? I have never used foam in this manner; pour in or pieces that are sanded. I would be concerned you wouldn't get the "best" stiffness unless you were concentrating on the adhesion between deck and bulkeads vs. deck and foam surface. Thinking out loud, that's all.

Later,
Ball

[785boats]

I'm waiting on some epoxy to arrive. When it comes I will start this fine toy boat.

So it won't be long then Ray.

Heath.
This will be EA Sports Hydro.

Ball.
I always shape & sand smooth & level with the framework.
It's the best of both worlds then. The epoxy bonds to the framework & the foam. Solid as.
The caveat is to leave the foam for a few days in some nice heat to make sure it has fully expanded BEFORE a final sanding & gluing on the top skin.

[ray schrauwen]

So it won't be long then Ray.


Ball.
I always shape & sand smooth & level with the framework.
It's the best of both worlds then. The epoxy bonds to the framework & the foam. Solid as.
The caveat is to leave the foam for a few days in some nice heat to make sure it has fully expanded BEFORE a final sanding & gluing on the top skin.

Epoxy should be here tomorrow.

Since I use cut foam and glue it inside the sponsons and elsewhere, I do not need to worry about expansion.

When sanded even with bulkheads the top skin sits evenly on both. I take lots of time to make sure its right and then I deck it.
I first coat the foam and let epoxy soak in for 1/2 hour while the bottoms of the decks get a coat too. After a 1/2 hour I add a bit more fresh MAS epoxy to both and then bond with clamps, weights and tape. Unless it's a spec boat, I build my hydro's a bit heavy, less lead required.

[T.S.Davis]

The caveat is to leave the foam for a few days in some nice heat to make sure it has fully expanded BEFORE a final sanding & gluing on the top skin.

Complete expansion is the key. Small batches helps. The foam adds weight but if weight's not an issue..............it's like building a sponson out of concrete.

That foam is so strong it becomes one with the frames no matter the intent.

Mike, the old led sled Whip was built this way back in 2008. Raced it this passed summer in P sport. There are holes in the sponsons. It doesn't care.

[TRUCKPULL]

Here is the way I did my Mini Wip. (Foam cut into pieces, and glued in)

It is rock solid.

Larry

[785boats]

So there you go Ball, a couple of different ways to achieve the same result.
Any extra weight in the sponsons is a bonus for us here in Australia because we are only allowed to race with a 1P pack with a max weight of 650 grams. So extra weight is usually required to get the balance right. Less added weight is required if the front half of the hull has some weight built into it. But the low density foam I use is not very heavy anyway.
The foam I use along the sides is just that white beady "koolite' foam, like fruit packing boxes from the local produce market. Super light.

[longballlumber]

Different strokes for different folks...

[Scott T]

Great build as usual Paul, looking forward to seeing it run next season :smile: I really like this hull, Shooter has done a nice job

[785boats]

Thanks Scott.
Yep. It's definitely a nice kit & cowling.

[T.S.Davis]

My build will barely have enough foam to float.

[785boats]

I certainly like to have enough foam in there to be able to float with the tub totally flooded.
I've seen too many boats sink because of not enough floatation. A couple of my own included in my early days.

After coming home from work today I made the leading edge piece for the tub, and epoxied on the top decks.

The leading edge was made from some Meranti that I had lying around. It wasn't quite wide enough so I had to add a couple of bits of ply to make up for it.
Then I bored a series of 12mm holes through it lengthwise & crosswise to lighten it up a bit as per the instructions.
I then saturated/sealed the inside with some clear spray urethane.

The underside of the decks were given a thin coat of 30 minute epoxy, as were the frames of the hull, & the skins were clamped, taped, & weighted into place.

[Shooter]

My build will barely have enough foam to float.

:banana:

[bozo586]

My build will barely have enough foam to float.

i think you had one of those before----you got a couple of laps in----kissed lots of money good bye! might be second time around----good luck!:doh:

[785boats]

A few more bits done yesterday & this morning.
The nose block epoxied on & the decks trimmed & sanded to shape.
I trimmed up the hatch & cowlings to fit, & then glued the lower nose piece to the upper piece with some Plastruct Weldene.

Now it's time for some final sanding & filling & some glasswork along the joints in the tub & the battery compartment.

[ray schrauwen]

Thanks for all the pictures. It's nice to have someone else start first. Looks like I'm stuck doing nothing until after Christmas.

[785boats]

No worries Ray.
But the photos in the instruction PDF that Pete has made are pretty comprehensive. Especially with the notes written on them.
Why can't you get started before Christmas?

[ray schrauwen]

Finishing an ML265 hydro first and things to do for Christmas so my gf doesn't have to do so much. Doctor said take it easy for a month after I had a mild heart attack a few weeks ago. My batten sticks are back nat my apartment also so not going there until tomorrow and back here in a few days. I'm spending a bit of time at my gf's place while I heal up my heart.

[Shooter]

Ray,

Sorry to hear about that. Rest up and take care of yourself!

[785boats]

Yeah mate. Take care of that heart. Have a nice relaxing Christmas break.

[T.S.Davis]

It's just toy boats Ray. Build those at your leisure because they make ya grin. Get better first.

[ray schrauwen]

Wendy likes it when I build and she helps a lot too.

I try to get a 1/2 hour in on the days I'm up to it. I feel fine although I tire out easy.

Thanks for the kind words guys.

[TRUCKPULL]

Wendy likes it when I build and she helps a lot too.

I try to get a 1/2 hour in on the days I'm up to it. I feel fine although I tire out easy.

Thanks for the kind words guys.

Ray - leave Her alone and concentrate on the boat. You won't get as tired.

Larry

[ray schrauwen]

.........:banana: Doc says no hanky panky for another week :bounce:

[785boats]

Wendy likes it when I build and she helps a lot too.

Wendy sounds like a real treasure, Ray.

Finally got the glasswork done on the edges of the tub floor, mount & the battery area.
Also gave the outside of the hull a couple of coats of sealer thinned down.
I've taken to using a two part epoxy wood preservative on my last few boats. Thinned with Methylated Spirits, the first coat soaks right into the wood. After a light sanding to remove the fuzz, the second coat leaves a nice surface for the primer when sanded.
Now it's time to set up all the hardware & drive line.

[Shooter]

Paul, you've got some serious skills. Your boat is really looking good!!! Nice job!!!

[785boats]

Thanks for the compliment Pete.
I guess it comes from my love of scratch building scale models.
http://forums.offshoreelectrics.com/album.php?albumid=320

[Shooter]

I'm loving that Typhoon!

[ray schrauwen]

Wendy sounds like a real treasure, Ray.

Finally got the glasswork done on the edges of the tub floor, mount & the battery area.
Also gave the outside of the hull a couple of coats of sealer thinned down.
I've taken to using a two part epoxy wood preservative on my last few boats. Thinned with Methylated Spirits, the first coat soaks right into the wood. After a light sanding to remove the fuzz, the second coat leaves a nice surface for the primer when sanded.
Now it's time to set up all the hardware & drive line.

Wendy is my soul mate, very lucky to have her.

Your glassing skills are quite impressive. I might try that.

Is typical fiberglass tape around 2 oz material? I have some and don't know its actual weight. After Christmas I'll head to PJ Hobbies to see what they have kicking around.

[785boats]

I'm loving that Typhoon!
She is a nice old boat, Pete.
But unfortunately I can't take credit for the actual build. It was a static wooden model that I converted to R/C.

Ray.
I don't know what the weight is. All the description says is that it is 0.13mm thick. But it's not too heavy because it tucks into the corners nicely.
http://www.ebay.com/itm/Fibreglass-cloth-30mm-wide-30m-long-rc-boat-/150784733013

[TRUCKPULL]

Wendy is my soul mate, very lucky to have her.

Your glassing skills are quite impressive. I might try that.

Is typical fiberglass tape around 2 oz material? I have some and don't know its actual weight. After Christmas I'll head to PJ Hobbies to see what they have kicking around.

Check Here
1 Sq. Yard 3/4 oz.
http://www.offshoreelectrics.com/proddetail.php?prod=dh-hcar5000

1" wide 2 oz. tape
http://www.offshoreelectrics.com/proddetail.php?prod=ose-80977-25

2" wide 2 oz. tape
http://www.offshoreelectrics.com/proddetail.php?prod=ose-80977-50

1 sq. yard 2 oz. cloth
http://www.offshoreelectrics.com/proddetail.php?prod=dh-hcar5010

Larry :canada:

[Shooter]

Larry,

Are these fiberglass tapes self adhesive? That would be a great building tool.

[TRUCKPULL]

Larry,

Are these fiberglass tapes self adhesive? That would be a great building tool.

NO they are not, but it would be nice.

Larry :canada:

[ray schrauwen]

She is a nice old boat, Pete.
But unfortunately I can't take credit for the actual build. It was a static wooden model that I converted to R/C.

Ray.
I don't know what the weight is. All the description says is that it is 0.13mm thick. But it's not too heavy because it tucks into the corners nicely.
http://www.ebay.com/itm/Fibreglass-cloth-30mm-wide-30m-long-rc-boat-/150784733013
I have this is that is what I'll use. I have a few square feet of 3/4 oz cloth somewhere too??

[785boats]

Catch up time.
I've fitted all the hardware now. I find it best to drill all the holes before I get the final paint on it. Mistakes are easier to fix that way.

Rudder & strut were drilled, tapped & bolted onto the transom.
The ESC & safety loop were fitted into the side compartment near the motor.
I added a ply doubler where the stuffing tube exits the boat. Then the stuffing tube was bent & glued in with some JB Weld.
The servo was fitted & connected to the rudder with a 3mm steel rod & ball joint.
I had a turn fin lying around but no bracket so I made one from some 4mm Aluminium angle & drilled & tapped that onto the heel of the sponson.
Here's a few pics to show how it ended up.

[TRUCKPULL]

Paul
Nice Turn fin, is that stainless steel??

You use a Mono strut rather then a Hydro strut??
I thought about that myself (moving the prop a little farther back)
Have you used this before, how does it work compared to the Hydro strut?

I like the little after- plane on the rear also.

Larry

[785boats]

Hi Larry.
Yep. It's a stainless fin. We are lucky enough to have a guy in our club that can make any type of fin you want. It was in my spares box & I've used it before on a similar sized hydro, so I bolted it on to this one.
The rudder & strut were also in the spares box. So I used them. That strut works well. It only moves the prop back 7mm more than a standard Speedmaster .21 strut. I've used them on other hydros without any problems. I haven't tried both types on the same hull though so I don't know of any advantages or disadvantages either way.
That little overhang has been on a couple of other hydro kits I've built so I thought I'd leave it on this one too. I don't know if it does anything but it looks good.

[b0atnutz3]

What Esc are you using and size?

[785boats]

b0atnutz3.
That's just one of my ever faithful Sea King 180A ESC's.

[785boats]

Well she had her first shot of colour.
I know some of you will hate it, but I've become a fan of pink & green lately.
My Miss Penrite is a striking boat out on the water.

[ray schrauwen]

So is that a vacu-pickle canopy?

[detox]

You build very fast...were you doing meth?

I once repainted a hull three different times. The old paint acts as a verygood filler, but makes boat heavier. Too heavy hull weight is not good. Too light is not good either.

[detox]

Legal Sudafed (Equate brand) acts good as a mild stimulant when building.

[785boats]

So is that a vacu-pickle canopy?

It is on the Penrite.
But this boat, the 'SharpShooter' will have the cowl that Pete supplies with the kit.

detox.
Just coffee. None of those artificial drugs for me. Just the organic stuff.:wink:
The last boat I repainted was that Penrite boat in the pic. I wiped all the old paint off with paint thinners & a lot of old rags.
Where we race, it is windy & rough water more often than not, so a bit of weight built into the hull is a good thing.
I should weigh the hull now that it is all stripped down again to get a comparison with other builds. I'm sure it is on the heavy side. I hope so, because we are only allowed 650 grams of 1P battery, so it will need some extra weight.

[Shooter]

Wow, this thing is looking great......and I like the color!!! My next boat (after the black pearl IV), will be pink!! Look out MMEU guys!!

That fin looks beautiful. Just a suggestion if you don't mind though....you might need a little more curvature. Mine hopped in the turns with a fin very similar to that.

Oh, regarding your other question. I run an H5 prop with the NEU 1515-1Y.

[785boats]

Thanks Pete.
I'll add a bit more bend near the bottom on the fin.
Thanks for the info on the prop & motor. The H5 is possibly my favorite prop on a sport hydro. Both that & a Castle 1515/1Y are powering that Miss Penrite in the pic. I'll swap them out into the SharpShooter when the time comes. I have a TFL SSS 4082 2200kv motor I could try too. But I think the Castle might have a bit better efficiency, & a touch more pepper.

[785boats]

Well the weather has been fine lately so I finished off the paint & added a few decals. So here's the SharpShooter in its final livery.
Just need to refit the hardware & test her out.

[TRUCKPULL]

Looks GOOD Paul.

Larry

[ls1fst98]

Nice!!! Real men love pink. I will do a kit one day I swear. I get a great feeling of accomplishment building and this would be more so

[Heath M]

Very nice

[785boats]

Nice!!! Real men love pink. I will do a kit one day I swear. I get a great feeling of accomplishment building and this would be more so

Thanks guys.

ls1fst98.
Pink is becoming my team colours I think.
This would be an easy kit to start with. The instructions that Pete supplies are clear & concise with lots of pics.
The kit fits together nicely & the cowling fits perfectly when it is all trimmed up.
Don't say "one day" or you'll never do it. Be like the Nike slogan. "Just Do It".:biggrin:
Actually, I saw a T shirt, while on holidays, that said "Just Did It." I like that one.:thumbup1:

[Shooter]

She looks beautiful!!!!!! :tiphat:

[Doby]

Thanks guys.

Pink is becoming my team colours I think.
:

Boat looks nice, but does it come in men's as well???

[785boats]

Glad you like it Pete. It turned out pretty good.

Hey Doby.
Only real men can wear pink.:lol:

[jwt]

Paul

Real men wear Salmon not pink colour!!!

tms
Glad you like it Pete. I turned out pretty good.

Hey Doby.
Only real men can wear pink.:lol:

[Doby]

https://www.youtube.com/watch?v=on_D7-l7GTw

[785boats]

So my orange shirts are "Mandarine" & my yellow shirts are "Lemon":lol:

[Speed810]

Paul...

Just stummbled across your build here. That build actually went really quick and its looks Great!
I actually just started on mine over the weekend. I have also been pretty impressed on how quickly the framing has moved forward. I think most of my time was spent putting together the prep board, jigs and clamps to make sure everything was staright. So now I have Mike's ML GSX380, just finishing up the bottom skins and now the shooter in the framing phase.

You have any tips on making sure things are squared up when adding the sponson framing? I'm at that point now. I don't have a problem with squaring up the sponson bulkheads to the working surface....just wondering if there is anything I need to keep an eye on when installing the main outter sponson rail? Or do you just line that up with the tip of the inner sponson frame tip and your good to go?

Again great job on the Shooter!!! I Love the Pink paint job. Worked over at Oshkosh, WI for the EAA Fly-in as an air traffic controller for 14 years and we had to wear the pink shirts everyday. I kinda liked them....:)

Good talking with ya again...

Mike

[785boats]

Mike.
I just drew two parallel lines on the board for the main rails with a line at 90 degrees to them for the main rear sponson bulkhead & one for the transom.
This keeps everything square & parallel. Then I simply used a small set square to get the rails & bulkheads square to the building board & held them in place with weights. Then tacked all the joints with ca.
The sponson bulkheads just seemed to line themselves up when put in place. Again, I just dry fitted the sponson bulkheads & chine piece, checked everything was square & parallel & tacked all the joints with ca.
Pete would give you a better procedure if you contact him, I'm sure.

Pink is an easy colour to see out on the water especially if the boat is up side down. Glad you like it.

EDIT:
Sorry I was thinking of a different kit.
The first sentence is wrong.
I drew a centre line not two parallel lines, & the main sponson bulkhead hung over the edge of the building board.
Sorry.

[785boats]

First test run on our clubs first test day.
Straight off the bench she was fast & accurate with great stability in the turns. That was with an ABC H-5 prop.
She was running a bit heavy on the sponsons so I lifted the strut a bit & put an M547 prop on hoping for a bit less lift in the tail.
Still a bit wet, so I tried a 447 & raised the strut a bit more.
The wind was up & the water was pretty choppy, so not really a good day for testing set ups. But I was happy with it at this point so fellow club member Trev was going to take a video but unfortunately I hit a buoy in the first turn & flipped.
Even worse, the front part of the cowl broke from the impact (she hit at full noise) and half of it sank. The front part, with the foam in it, was retrieved but that will be trashed.
Fortunately Pete had the good grace to send me and a fellow club member who also has the kit, a spare cowl each some time ago, so it's not such a big deal. Thanks Pete.
I just need to trim it up & give it a clear coat.

[Shooter]

Funny, I smacked a bouy my maiden run as well!!! Embarrassing ----> https://www.youtube.com/watch?v=iuqf-BGNr2s

Sorry to hear about the crash, but happy it's running fast and stable. That was my goal with the angled vents and wider stance.

[detox]

Too wet is a classic mistake...strut set too deep...too much weight up front.

Bottom of hull should be level with board (hull resting on rear of sponsons and strut). Sometimes I have to file strut slot to allow for less deep setting..

Hang hull sideways using finger at middle of turnfin . Ready to run hull should hang level or very slightly tail heavy. This is your balance.

Turnfins are tricky. Too much inward angle is slow.

Running too wet also caused my UL-1 nosecone to pop off when hitting waves (strong nose cone did not shatter). Adding a locator pad helped prevent nose cone from shifting and breaking tape. Pad shape looks just like Aquacraft's UL-1 version.




....

[785boats]

Pete.
I was more than happy with it. A few more sessions of testing & she will be a happy little runner. I think the M447 was going to be best prop for the day but didn't really get to try it out because of the sudden deceleration issue with the buoy.

detox.
Not really a mistake running it a bit wet on the first runs. I like to start with it that way rather than watching it blow off the water the first time down the back straight because the set up was too loose.
I raise the strut a bit each run & /or change props to ones with less lift until the sponsons are just breathing on the water. That's just the way I like to test new boats.
I prefer to have the cog at about 1/3 the way forward from the trailing edge of the turn fin & that's where it was with the pack at the rear of the battery compartment.
The turn fin was working well. Nice tight turns at full noise with no loss of speed.
It was a good day.

[Shooter]

This boat is no doubt more prone to run wet. Every boat on the market at the time packed too much air for P sport IMO, so I threw everything at it to reduce the pressure under the hull (angled bleeds, low tunnel depth, etc...). As you reach speeds of 65+, this will be a huge benefit!!

BTW - I've raced this boat for two seasons. Never had a blow over. People tell me I'm running too wet, but I've also finished every race!! :thumbup1:

[Speed810]

Paul....Sounds like you have a keeper there... Sorry about the incident with the buey. I hate those things sometimes....but trying to keep that depth perseption out there can be a pain....been there!

When you say:: I prefer to have the cog at about 1/3 the way forward from the trailing edge of the turn fin. Not sure I understand that. I have always measured back from the trailing edge of the sponson to the center of the turn fin. i.e. My 1/8 scale I have balanced out about 1"1/4 from the trailing edge of the sponson which puts it at about the center of the turn fin. Just wondering if this another way to balance these boats. I know my 1/8 scale does run somewhat wet.

During my balance process I used a 1/2" steel rod, placed it under the hull at equal points on each side and shifted weight around until I was able to hit the 1" to 1"1/4 mark.

In any case it will be great to see a video of yours running....

Mike

[785boats]

Mike.
I will post a video as soon as I can.
All I am saying is that instead of the cog being in the centre of the fin I have it a bit further back at 2/3 of the fin from the heel of the sponson.(in other words, 1/3 of the width of the fin forward from the trailing edge of the fin).
But the fin I'm using on this boat is only 1-3/4" wide & is mounted as close to the sponson as possible which puts the cog at about 1-1/2" behind the heel of the sponson.
In my other hydros, the little bit of extra weight behind the fin seems to help throw the tail out more easily in the corners with less rudder throw & therefore less drag & more speed in the corners.
But the aero effects of this hull seems to keep it well planted so I might have to slide the cog forward a bit to free it up a little. It never even felt as if it was going to lift off. We'll see in the next practice session.
Maybe I'm wrong with this Pete. Where do you have the COG on this hull?

[Shooter]

To be honest Paul, you guys probably know a lot more than me regarding trimming a boat. I do know that a fin forward of the CG will be more 'effective' than a fin behind the CG, but I prefer my fin to be right at the CG so the reactive force on the fin is acting through the CG (if the force is behind the CG, the moment arm is fighting the rudder in the turn and it will be more stable, if the force is in front of the CG, the moment arm is spinning the boat and adding more steering). My CG is at about 1" from the back of the sponson which is actually a little in front of the fin center.

[detox]

Changing COG is as simple as adding stick on lead weights...especially to rear of hull. Sometimes you can tell quickly if it works or not.


I wonder what works best, a lightweight hull running a tad tight, or a heavier hull running a tad loose? I think in most water conditions the heavier hull will work best.

[T.S.Davis]

To be honest Paul, you guys probably know a lot more than me regarding trimming a boat. I do know that a fin forward of the CG will be more 'effective' than a fin behind the CG, but I prefer my fin to be right at the CG so the reactive force on the fin is acting through the CG (if the force is behind the CG, the moment arm is fighting the rudder in the turn and it will be more stable, if the force is in front of the CG, the moment arm is spinning the boat and adding more steering). My CG is at about 1" from the back of the sponson which is actually a little in front of the fin center.

Didn't we talk about this one one of your early versions?

You can tune your turning by fiddling with the position of the fin in relationship to the CG. Slide the fin forward and the rudder has more effect etc.

[785boats]

^^ That's what I was trying to say in my post #80. GoG nearer the trailing edge of the fin helps with the turns.

Detox.
Weights are always an option, but I'll see what I can do with the strut depth, angle, & props first.
I must admit that most of my hydros needed weight added to the front. But this one might end up needing some at the rear.
Where we race the waters can be very choppy most of the time & you are right, the heavier boats certainly fare better in those conditions. That's why I don't mind if my boats are slightly on the heavy side.

[detox]

Getting the boat to track strait as possible without fighting rudder is important. I check this on water before and after turnfin is installed. Bending of strut (left or right) and turnfin bracket may be required.

Next I would check strait line speed by adjusting strut depth and COG.

Finally I would adjust turning. I like TSDavis's idea of moving turnfin forward and backward when testing.


...

[Shooter]

Didn't we talk about this one one of your early versions?

You can tune your turning by fiddling with the position of the fin in relationship to the CG. Slide the fin forward and the rudder has more effect etc.

Yep. I remember we were out there one Saturday afternoon moving it forward and back. I was really surprised how much effect it had with only a 1/2" shift!