Black Pearl II Hydro - 2020

[TRUCKPULL]

Where exactly do I mount the rudder on this Hydro? A whiplash is easy since it has he rudder on the edge of the upper tub.

Ray
As far to the left as you can, so your rudder mounting bolts are on the inside of the front to back (inside) bulkhead.

Larry

[ray schrauwen]

Than you kindly sir! The pictures help a lot.

Including the one you are working on right now, how many have you built?

[TRUCKPULL]

This will be my #14 Wood Sport Hydro.

Larry

[ray schrauwen]

How much weight does the turn fin actually see in a turn?

[T.S.Davis]

HA! I made a spread sheet for this.

Number of factors to consider. Speed, weight of boat, then diameter of the turn. With that you can come up with G force. That math assumes a perfect world though. There were too many missing pieces in my formula. You enter at say 70 mph. Apex at 45? Not sure. Then......how much actual slide happens with the fin. Sorta like prop efficiency. Props don't give us 100% grip on the water they pass through. Same with a fin. You may do a 40' radius turn but the speed changes through the whole thing.

If you turned a perfect 40' radius at 60 mph..............you end up at 2.81G. That weight is hanging/sliding on the fin and the rudder......sorta? There's also the angle of the fin. The shape of the hook. Is the hook lifting in the turn or pressing into the ride pads? Are the sponson edges doing anything? Depends on that lift again.

Clear as mud.

There's likely a way to figure it out but I quit farting with it. Figured I'd burned enough brain cells on it.

[Rlimits]

Now how about the rudder that keeps bending after running.

[ray schrauwen]

Jeese... ask a simple question.... lol...

I'm just going to copy this. https://www.mojoracingproducts.com/c...rt-hydroplanes I don't want to bother with an adjusting rod like Larry and some others use... I have some 1/4" material but the buggers cut it 1-1/4" high so I have some material to remove the hard way...

[lohring]

You can use a version of the pictured system to hold the turn fin straight. That's what I'm using on my Black Pearl.

Lohring Miller

Anderson Sp 40 rt side 2003.jpg

[TRUCKPULL]

You can use a version of the pictured system to hold the turn fin straight. That's what I'm using on my Black Pearl.

Lohring Miller

[ATTACH=CONFIG]176940[/ATTACH]

Lohring - your picture is not a Black Pearl.

Larry

[ray schrauwen]

You can use a version of the pictured system to hold the turn fin straight. That's what I'm using on my Black Pearl.

Lohring Miller

[ATTACH=CONFIG]176940[/ATTACH]

Larry does it in a similar way. I'm not sure I'm into breaching the hull there. What if the rod starts turning instead of adjusting? I need a diagram or something to understand how that rod stays put when you try to adjust it.

[lohring]

Lohring - your picture is not a Black Pearl.

Larry

The picture is of an experimental Mark Anderson sport 40. I don't have a picture of my Black Pearl but this is a similar size boat. I anchored the hull end that goes into a blind nut with a lock nut that keeps the threaded rod from turning. Two nuts on either side of the turn fin end allow adjustment and can be locked against each other. You can see the hull side lock nut and the outside adjusting nut in the picture.

Lohring Miller

[ray schrauwen]

Thank you. Last question. Is the blink nut and a lock nut on the inside of the hull ?

[lohring]

Thank you. Last question. Is the blink nut and a lock nut on the inside of the hull ?

I don't remember, but I don't think so. Maybe the only lock was the two nuts on the turn fin end. Below is the setup on my Mutt sport 40 and Black Pearl. I used a threaded rod into half of a turnbuckle. The hull end goes into a threaded insert with a lock nut. The turnbuckle has a lock nut on one end and a 2-56 tapped cap screw holding the eye into the turn fin bracket. The sport 40 picture I posted is a simpler system.

Lohring Miller

P1010006.jpg

[ray schrauwen]

O.k. thanks I got it now. I was also talking to Larry yesterday and he explained a lot.

[T.S.Davis]

I haven't bothered with trailing edge fin support on a P boat. I did do it on my Q whip though. The one with no transom has a support at the end of the turn fin. I put a piece of aluminum backing inside. Drilled and tapped the aluminum through the hull. Bullet proof......until the deck rips off of course.