AB Marine Intimidator Endurance Boat

[Peter A]

Well it is finally finished, this year's offshore boat.
The Hull is an AB Marine Intimidator 45" mono that has been rebuilt from a gas oval racer for Offshore endurance racing.
Motor is a Leopard 5692 540kv, esc is a SK 130 HV, it will run both 10 and 12s.

163406163407163408163409163410

[Peter A]

A few more pics. I hope to start testing next weekend.

163411163412163413

[Peter A]

And this is what I started with.

163414163415163416163417

[fred 75]

Great job Peter! :thumbup1:

[srislash]

Looking forward to this years results Peter. Great work as per usual.

[Bp9145]

That turned out very nice. . .nice work!

[Peter A]

Thanks guys. It is not quite so perfect when you get real close, but it is going racing so it will almost certainly get it's share of scrapes and dings. That's why I keep it simple! Can't wait to get it on the water.

[Peter A]

So the boat got on the water Saturday. Running a P240, same as the old boat, but on 12s, speed was 75 kph max. Unfortunately current draw is too high at around 70A. On 10s the current draw dropped to around 56 A with a max speed of 64 kph. Temps are a little higher than I like. Unfortunately I do not think the Leopard motor is the one for this job. Definiitely a lower kv and bigger prop will be best as on 12 s with a P235 speed dropped to high 60 kph but current draw increased as well. A new learning curve.
I will be looking at getting the TP 4070 440 kv 10y motor. There are, as would be expected, a few other tweaks to do on the boat as well. Other than that, the boat ran well.

[Peter A]

Well, new motor is ordered from TP, will not be shipping until Feb 12 though. I guess they have to make it! More parts ordered also from OSE. I will update when things have been able to progress.

[785boats]

Hi Pete.
I would have thought that a 6 pole 56 series motor would have been more efficient (current wise) than a 40mm 4 pole motor of the same kv rating.
Is this not the case?
We are thinking of starting an endurance class at our club. I was going to try a 6 pole 56 motor of 500kv.

[Peter A]

Hi Paul
The Leopard is too high in kv when trying to match prop to the boat on 12s. On 10s it was close, perhaps would have been right for amps but for the thrust bearing behind the collet that was disintegrating! However from what others are doing on 12s I think I need a lower kv to turn the larger prop this hull needs to be efficient. For me the average current draw is more important than overall speed.
When the going gets rough, and I run against petrol offshore boats, I can hold my own. For all the boasting about top speeds, the gassers are only averaging around 70 kph tops on open water, and I managed to keep up pretty good in the rough. My Osprey really held up well in water that was up to two foot waves against the gassers, taking out 5th of 19 at the biggest event last year. I had propped down and was running 1/3 to 1/2 throttle, battling much bigger boats of which some seemed to try and take me out!

What sort of setup and race duration are you guys looking to run?

[785boats]

Sounds like a great result against the gassers.

We are not sure on the run time or max battery capacity yet so it is still all up in the air at the moment. Still in the "talking about it" mode.
I have an Osprey or a big cat I can convert. We are all trying not to spend too much money & use the boats & battery packs that we have.
One of us will have to set one up & see what sort of run times we can get with different battery configurations.
Bear in mind that we are not racing against gassers & it is only within our club.But we are still governed by the AMPBA regarding max voltage & battery configuration.

[Peter A]

My Osprey went great with a TP 4060 580 kv on a P240 prop. Speeds 65-70 kph and current draw at 50A. With 10s 20000mah that gave 20 min runtimes, 16000 made 15-16 min. I am unsure of the AMPBA rules, but going electric endurance will take you out of that box if you want 20 mins races. Going to lower kv on 12s will give longer runtimes. I am not sure that the 56mm can motors will run a low enough current draw, and 40mm can motors fit existing mounts in most boats. An extra reason for going for the 4070 motor, I can always put it into my Osprey if needed and run that.
I have to say though, this is quite a fun way to change up FE boating. The concentration needed to run longer races, albeit at lower speeds is a challenge at times.

[Peter A]

Look what turned up yesterday direct from TP Power.

163920

Will get some plugs on it and installed on Saturday. I have already fabbed up and installed brackets for the OSE quick change mounts, so it will not take long to install. Hopefully I can get back to testing next week.

[Peter A]

Got back out on the water on Saturday with the new 440kv motor installed. Running a Prather 245. Max speed 65kph, ok. Temps, motor and esc maxing around the 30*C mark with batts just a couple of deg higher. Ambient temp aroung 23*C. Boat ran well, first did a ten minute run, then a 20 min. I am using the RCM telemetry and it helps me keep an eye on temps and batt cell voltage. Average current draw at 52 amps. A nudge above what I want to achieve but I might be able to reduce that by changing the stuffing tube as it gets rather hot, even though it is greased and has a pressure grease system. I think the length is part of the problem. If I move the motor back much further and reconfigure the inside setup, I can get the CG a bit further forward using batts only with out using more weight, and possibly reduce some of the weight that is in the boat. A lot of work on a new setup, but might be the best result. Option two is change the stuffing tube to one that is a bigger diameter, which is much less work but possibly not the better end result.

164090164091

[Peter A]

Burned up the motor on Saturday. I fitted some trim tabs during the week. To drill the transom I had to remove the rudder, but for some reason did not plug the cooling lines back in and totally missed it. 110*C on the motor and it is toast. Magnets are stuffed and wiring had that 'cooked' smell. On the up side the trim tabs did the trick and improved the ride and turning. Ordering a new motor today and I will be back on the water in a two-three weeks with this boat.

[tebby2]

Peter,

Sorry to hear about the cooked motor. It took me 2.5 months to receive my TP 4070 10Y motor after placing the order. Did you move the motor aft and shortened the length of the stuffing tube after installing the trim tabs, or did you keep the motor forward with the battery pack aft as in the picture?

Charlie

[Peter A]

Hi Charlie
I should have the motor in about two weeks. The first one took nearly a month due to Chinese new year. I have found TP pretty easy to deal with. Actually I have two motors coming as the one in my Q hydro decided to lunch it's rotor and take out the esc that same day as well.
No I have decided not to move the motor at this point, it is quite a lot of work. I have made up a new stuufing tube with teflon liner and will run oil instead of grease. I am thinking about putting bearings in the stinger instead of bushings also.

[Brushman]

Hello,

the TP 4070/440 can be used, but you have to optimize your boat until you get 70 KpH and 50A average, if the current is excessive, this motor is not the best and a larger one shoukd be used. You should also try a 4035/400 Xnova lightning, this is a good outrunner. But of course you need to reduce the amp draw before trying other motors. A video of your boat will help to see what should be optimized. About the liner, if you have a teflon liner, do not grease it, it is a cause of drag...

Vincent

[Peter A]

Hi Vincent
With the 4070 440kv motor the current draw is down to 52 A. While waiting for a new motor to arrive I have made and fitted a new stuffing tube with teflon liner. It will be lubricated with an oil feed. I will also do a little work on the prop and detongue it and that should bring down the current draw a bit further. I am ok with the current speed at 65 kph, any extra would be a bonus, however when the water gets rough you cannot use the speed anyway, and the gassers slow down also. Some of the boats I race against are 60+ inches in length, even up to 72", and can top out around 100kph. I will never be able to compete in speed, but I can on reliability and consistency.
I just need more time on water to test and tune.
Perhaps this hull is not the most efficient, if all else fails I can always put motor/esc into the Osprey and run that!

[fred 75]

Personnally, I believe in your Hull...:wink:
As you said, you just need more time to test and tune...It takes time to get a result...

[Beaux]

Nice job, those 10- 20 min runs are great.

[Peter A]

New motors turned up yesterday, but this Saturday is 2-laps and speed runs so it will be next week before I install the new motor in the boat.

[Peter A]

Well after getting the boat back on the water Saturday, it ran ok like before. However, the boat porpoises a lot due to the CG being too far back is what I thought. So to try and balance the CG I glued an 18 oz (420 gram) sinker in the front of the boat. It was a little too mouch wight and I had to move the batts back a bit but no worries there.
NO GOOD! the boat still porpoises, worse when it gets going. I think the weight has a pendulum effect, so it was hard going for a twenty minute race yesterday. With my first offshore race of the year this coming Saturday I have two choices. Try and remove the epoxied (that is I dropped the sinker in the nose and poured resin in around it!) sinker, or swap the motor and esc into my Osprey, which does run well and I think is a better boat for the job.
This boat I think needs to either be reconfigured on the motor mount/batt position side of things, or just put a bigger motor in and use for Oval racing. I think changing over to the Osprey is a smarter move at this point. I can get things changed over the next couple of nights and be ready for Saturday.

[tebby2]

Peter,

Did your trim tabs not work well enough to smooth out the porpoising? I sound like you hull have a slight "hook" deflection with a full load of 2 x 6s 16000 mAh batteries and equipment. It was my impression the AB Marine Intimidator 45" was a better boat to challenge after the gas boys rather than a light weight 42" Osprey hull.

[Brushman]

Hello,

the reason for porpoising can be the CoG position, but assuming it is actually around 30-35%, this is not the problem. I think you have to blueprint the rear section of your hull. look for a "deflection" upward on last centimeters to the transom. Use some filler and make surfaces flat. This can take a few hours but it worth it. Still I am not sure because I do not know this hull...
Good luck!

[srislash]

Peter, I had a heck of a time with a DF 35 getting it out of the same characteristic. I ended up with trim tabs. Just barely in water but it fixed it. My Pursuit hulls totally don’t need them.

[Peter A]

Ok so the hull is pretty good at the rear, to be fair it is probably better than the Osprey, but I will check it over still. It is a much larger hull overall than the Osprey, and I expect the Challenger 43. Those extra inches lengthwise and width make a lot more boat. What I have found is that is cavitates a lot getting up on a plane, and it really is designed to be running props in the 67/3 size range. A P245-250 is a lot smaller. I will see how the Osprey goes on Saturday but will probably continue with it for the season. I think I will be faster with better current draw/runtime. There is no point running a boat that is trouble. I will probably just put the TP 5680 motor I have in it and use it for oval racing and/or sell it on.

Shawn I have a DF35 also. I originally set it up for 6s but have changed it to a 4s setup. I set the motor quite far back and had a CG problem with the 4s setup so have a couple of fishing sinkers jammed in front of the battery tray under the pool noodle. Much better. At our 2-laps I just missed breaking my record set with a pursuit 4 years ago by 0.4 sec, but I did spin the boat before crossing the beam so lost a bit of time there. Now I have to prep another x447/3 as that prop got folded up on the side of a 72" 'ship' on Sunday. Fortunately I have two more of those props.

I have found from experience so far that 32% is the 'magic' number for CG. It keeps the boat flat when it jumps on waves and wakes. Too far back and the boat will come down on the back and dive the nose it, too far forward and it will bow steer and nose in. for flat water speed running the CG can come back a bit but this can tend to help induce chine walking.

[785boats]

Pete.
What is the angle of the strut in relation to the keel.
I find that a slight negative angle can get rid of porpoising.Sometimes the cog might need to be moved a tad further back too, with a slightly negative angle.

[Peter A]

Hi Paul
Now the boat is sitting up out of the way it is clear to see I had way too much positive angle on the strut. How ever I changed over to the Osprey and will run that again this year. I have the option of changing boats but I have to apply to the NZMPBA committee, however their condescending attitude (we allowed you to run electric (!!!), means I am not going there.

It was however a good move to run the Osprey, I took 4th overall for the day with 141 laps, that was behind 169-1st, 161-2nd, 146-3rd. I had a couple of glitches at the start of the first 20 min heat, the esc wouldn't arm and had to be re-calibrated to the tx, then the flex spun in the collet after half a lap, so after retrieving, fitted a new shaft and got 19 laps in. The next 20 min I managed 34 laps, only one lap behind the highest 20 min count on the day of 35 laps.

For now the Intimidator will get a TP 5670 650kv motor as I can bolt that in and run it as an oval boat, should help me retain back my open mono club title hopefully! Just need some more batteries!

[DanInWV]

I have found from experience so far that 32% is the 'magic' number for CG.


How is this measured? Length of hull, 30-35% total length from the stern?

[srislash]

How is this measured? Length of hull, 30-35% total length from the stern?
Yes the measured length of the running surface. Some hulls have a big overhang at transom but that is not included in the measure. EG: if hull is 41” and has a 4” overhang then it is 30-35% of 37”

[Peter A]

Ok, so after a few weeks of this boat sitting I have decided to get it ready for racing. It will be an oval racer for now, but it may be possible to use it for the original purpose later, we'll see.
So a bit of placing and balancing and what was clear was that it would not work out the way it is to get CG right.
So....
Saturdays mission, tear it out and redo.

Before.
165078

Gutted.
165079

End of the day.
165080

Now a few bits to do. I will make a tray for the rx and battery that will be removable but cover the stuffing tube, and I am waiting on some battery trays which I ordered on Friday and should see later this week.

[Peter A]

Done, ready for a run on Saturday and see how she goes.

165210

[srislash]

Woot, woot

[Peter A]

Got it on the water Saturday, no issues with speed, temps and runtime for ovals, it corners well too. Just has a problem with getting really loose at speed, I think the drive line needs to come up a bit to settle the hull in the water. I will fit a flood tube and strut, but I will live with it for club day this coming Sunday.

165233

[Peter A]

Well the boat had it's first racing yesterday. Straight out and won the first two heats, second in the third and slammed upside down in the fourth for a DNF. That is against bigger gassers.
That ticked me off as one boat tried to squeeze inside me when I was in lane one for the start, then cut across me for turn one and then his son cut me in turn 1 and I was out. Nothing like the same old people not holding lanes (basically cheating) to get in front! Fortunately no damage and the hatch seal works great.
Rant over, I was pretty happy with the way it ran. I had changed the turn fins and readjusted the stinger and trim tabs. It only used 2400 mah for a race on an X452/3. Next is change out the stinger for a flood tube and strut so the hull will settle better at speed and I can run bigger props. There is more in this boat yet.

[RayR]

Are you using a shaft oiler for these extended runtimes?

[Peter A]

Are you using a shaft oiler for these extended runtimes?

The original setup was grease, then changed to an oil cup with teflon liner due to heat in the stuffing tube. Heat=friction=power losses. The oiling system worked fine and was sufficient for 20 min runs. Now that the boat has been reset up for ovals I have gone back to grease.
In my Osprey which I am using again for endurance racing, I use grease and have a spring loaded pressure pot I made which continually pushes grease into the stuffing tube as it runs. This works well.

[Peter A]

Update. I have fitted a flood tube and am awaiting parts from OSE (hopefully see them today or tomorrow) so that I can finish the strut conversion and hopefully test this coming Saturday.
Will do some pics then.

[Peter A]

Ok so having changed to a strut/floodtube setup here is where I am at. If I set the strut down the boat chine walks at speed. When I lift the strut up the chine walk goes away but I get porpoising. Not short sharp porpoises but long bouncy ones.
I have tried adjustments to the strut height and angle, I find that a bit of negative is helping. I have adjusted the CG as far as 35% but that hasn't fixed it.
If I lift the strut too high the prop loses a fair bit of bite. I have tried different props and am running on a X455/3 atm. I have tried a ABC 2414/4 as the original owner reckoned a four blader used to settle it down.
It is only when at full throttle I get the porpoising. I could just prop down more and lose the top speed but I want to win! LOl. Actually I am winning and the top speed is better than the gassers, just want to get rid of the instability if I can.

Any thoughts anyone?

BTW I changed out the motor for a TP56110 650 kv and have gone back to 10s. I am running it so far on 1P for a heat race, but can go 2P for longer running or extra weight.

[srislash]

Geez this sounds like my DF 35”, man I fought with it just as you are. And pretty much same results. The only thing in the end was installing trim tabs. I did not want to run them but... and now it’s solid as can be. Took very little trim.
Another thought, a longer strut? Like get the prop further back from the transom. This thought since you mentioned the negative helping. Or how about a ABC prop with 15 or 17* rake?

[Brushman]

hello,

more weight can help to reduce porpoising, with the 2P setup?

[Peter A]

The boat has trim tabs, I hve tried with and without, the boat corners better with them but otherwise they don't have any real effect on the porpoising issue. The 2414 prop is 15* rake, the problem occurs when the speed gets up, I will have to throw the telemetry in and pinpoint where it occurs. I am using a long strut also. More weight is definitely the next thing to try, so I will run 2P next chance I get on the water. Just a matter of playing around untill I find the 'sweet spot'.