Osprey Offshore Endurance Boat

[SCARAB33]

Hello
the lipo hk multistar go well if you do not exceed 3C / 5C.
they have significant relief stages on the running time.
I just tested sl apl for 24h 2018, the discharge is constant and my speed remains linear from beginning to end, I get + time of navigation.
the quality of lipos is very important on a race of 24 hours, it is recent recharge because the lipo does not rest.
there are graphene, but I have not tested, some are hyper contant on the dump, the extra weight is not a problem for endurance, the price is expensive.
for endurance, lipos is the heaviest budget.

[Peter A]

Got a chance to go for a run this arvo. Pretty stoked, ran the 16000 mah batts. I am still charging the 4S pack to see how much it takes to fill back up, voltage when put on the charger was at 3.68-3.7V per cell. The boat weight with these batts is 8 kg, bang on. I was totally surprised that all the extra weight was not at all detrimental to the boats performance, even clocking a max speed of 70 kph, up a tad. 20 min run with temps all good.

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[785boats]

Looking good Pete.
I love the whole concept.

[Peter A]

Looking good Pete.
I love the whole concept.

Thanks Paul. It is a departure from the norm!

Interestingly the battery took 15900 mah to charge back up. I only charged the 4S pack as I know have to discharge it back down to storage. I am wondering about the actual capacity of these packs as the lowest the telemetry voltage dropped was to 7.1v under load. I had someone watching the screen. For those who are unaware, the telemetry system takes it's power from the balance lead of a battery, it taps just two cells hence the two cell voltage.

I realised yesterday that I have not even sharpened up the rudder or turn fins, or done any prep on the bottom!

Next testing will be for ovals, try some bigger props and aim for 85-90 kph for club day racing. On 10S 1P of course.

[Peter A]

Here is a pic from the first run. I have a short video file but not sure that I can upload it. Will work on that.

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[Brushman]

hello Peter,

I am happy to see this built, it will convince some electric boaters tht it is not necessary to have 5Hp under the hood to compete against gas boats...
A 16000 Mulltistar takes 17.5Ah from 3.3V/cell.
As said by Laurent, other brands are making better packs... at 2-3 times the Multistar cost! For this particular 24h race, multistars will do the job.
Best packs are the HK graphene 16000, charged at 4.3V/ cell, they will deliver 16.5Ah usable capacity. bad luck, they are discontinued...

If you try to go at 90 km/h, try to monitor the pack Temp's, or leave 25% in them...

You did a perfect choice on the hull for Oval, if the packs do not sag too much, you should win!

All the best!

Vincent

[Peter A]

Thanks Vincent.
I have gone for the multistar packs as they are reasonably affordable...and I can get them! It can be Limited/difficult to get batteries here in NZ, these all come from Australia and it depends what is in stock there.
When you say a 16000 mulistar takes 17.5 Ah from 3.3v/cell, what do you mean? (in simple laymans terms).

I will not be pushing to get 90 out of this thing, certainly not with the multistars! I think to get 90, based on testing so far I will have to bump up to 12s using revos, but just for oval racing.
For the endurance, speeds in the 65-70 range are enough. I am not out to try and win, although it would be a blast if I can beat the gassers, but I think it will need a bit of rough water and wind to slow them down, some of these guys are putting 7-10 hp in their boats! What they don't get is that works on flat water but when it roughs up they spend too much time getting rescued, haha, that's when I can do the tortoise thing! We have an offshore round in April so I am looking forward to see how things go. For sure I will update.

[Brushman]

Hello Peter,

a 16Ah Mulltistar is more a 17-17.5Ah pack.

yes, 90 Km/h is a lot for a multistar because you have only 10S, it can work on 12S for a short time.

12s on a 580 Kv 4060 will work with a 2114-15-60, but the motor is a liittle too small. a 4070 7Y would be better.

Vincent

[Peter A]

Hi Vincent
I am not too concerned about trying for 90, 80 something maybe for now but only with the smaller revo 5000mah for sprint racing. To be fair when getting to higher speeds in this size hull against gassers in the 60" plus size on an oval circuit all doing 80+ the water gets pretty hard to run in and the chances of stuffing or flipping are high. I just do my best to outlast and outdrive them as much as possible!

I picked on the smaller motor for lower current draws, and it has worked out as I was hoping, so that is all good. If I went for a bigger motor my concern is higher current draw which would be detrimental to the endurance aspect of this boat.

If the 16Ah multistar is underrated, how about the 20Ah ones? The extra capacity is good!

Peter.

[Brushman]

hello,

what is the race duration against gassers?

you noticed that the 3.3kg of multistars were giving a good handling to the boat, and run time was good? My advice is to put the same weight of lipo as low as possible in the hull 12s2p10000 for example, you will get more than 10 minutes and 80 Km/h, the only problem I see is the relative weakness of the 4060 for this 8kg boat. 8Kg is a good weight to fight against the gassers.

20Ah are 21Ah, and 4C constant discharge capable.

Vincent

[Peter A]

The races are either 20min, 30min or 1 hour. I will be able to do the 20min on 20Ah packs ( I did it on the 16Ah packs the other day, but it was a push!). For the longer races a battery change is required, that's ok. Current draw is 48-50 amps average. Race speed will be at the target 65-70 kph for the endurance racing. The extra weight is not a disadvantage for this, in fact on open rougher waters which are expected for three of the four regattas I will do each year, these are on bigger lakes which normally see a fair bit of wind. Wind speeds of 30-50 kph are not uncommon as is chop of over a foot. This is a great equaliser as the gassers have to slow down and I can prop down for lower speeds, longer runtimes and have the advantage of weight in the wind and waves.

For sprint racing I will not use the Multistars, I have revos 5Ah for that, so the boat is considerably lighter. I think I will get another pair of 6s revo packs to run 12s for sprints, it is allowed in our rules, and up to 12000mah, but the 5000mah is sufficient as the current draw is still only around 70-80 amps.

I went with a 40mm can in this boat as it can be easily converted with a motor change to a 6 or 8s setup. The 4070 7Y motor is not available at my normal suppliers currently. I think that if I build another boat in the future, I may go a little bit bigger and go for a 56mm can motor. But hey I have to prove the whole concept here first. Who knows, I may do well and get banned from running electric! (Yes, such attitudes exist here! It caused a stink when I asked to be able to race electric in the offshore series at national committee level!!)

[Brushman]

Hello,

understood, If the water is so choppy, you will get good runtimes and the added weight of the 20Ah will help. CoG will be critical to avoid nose dive in these conditions.

you will see for sprint, but if you run the Osprey on the same choppy water, a lighter hull will not help.

I am not a great fan of the 56 mm motors, they put a lot of stress on esc's and you need large capacity batteries, but it is probably needed for sprint racing...

good luck!

vINCENT

[Peter A]

After a bit of testing and racing it was time to 'bling' the boat.

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[Peter A]

I made a new hatch seal as well. Hard to tell from the pic.

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[Peter A]

Had the first offshore regatta on Saturday, 100 mins of racing. 2 x 20 min heats and 1 x 1 hour race. I did 131 laps, the winner did 157. I managed 5th overall in a field of 10 boats.
On Sunday, another regatta and I managed second in a 20 min race with 37 laps, the winner did 41. Not too bad racing against bigger petrol boats that are mostly faster and have way more hp.

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I had two unscheduled stops on Saturday, once when a plug came loose on the esc, left me dead in the water, of course someone had to run over the top of me on the front strait didn't they! Have a battle scar now! The second time I rolled upside down, when the rescue boat went out and turned me back over and I continued, well... Now some want a new rule to stop that from happening again. Gassers!!