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π¬ Re: Lorelei.... 1st pond trial
8 months ago by π¬π§ CB90 (
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I know this post is a few months old but I must say that the paintwork on this boat looks great.
On to its performance, I notice steering was difficult, I think this may be due to torque steer as out runner motors are prone to do, due to their large diameter. So a in-runner would be better, I used a 2040 for my NDK jetboat, the hull needs to be kept light as possible. Please check the inlet is shaped correctly, the water need to flow without much disturbance, no sharp edges to the inlet. Try to get the water level midway across the jet as this help it to start pumping water, otherwise it will just ventilate, (air and water) hence no thrust. Give the boat another look at, it would be a pity to leave it on the shelve.π€ Regards Roy ▲
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Colin H
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Remove Ads π¬ Re: Lorelei.... 1st pond trial
11 months ago by πΊπΈ cjanik001 (
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Thanks, we will see.
Anyway, it's another boat in my harbor, had fun building it, and will take her out again even if she is a pokerπ. ▲
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RNinMunich
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π¬ Re: Lorelei.... 1st pond trial
11 months ago by π©πͺ RNinMunich (
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Hi CJ,
" I might try to add a little weight to drop the stern down further. " That may help a little perhaps to get at least the forefoot out of the water. But I still don't think that that 15mm prop can generate enough thrust. Would be happy for you if your next video report proves me wrong. Cheers, Doug π ▲
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π¬ Re: Lorelei.... 1st pond trial
11 months ago by πΊπΈ cjanik001 (
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Thanks for the comments and suggestions. You are probably correct that the higher revs will not do anything, but at $16.00 U.S. gotta try it.
The larger jet was about twice the size, and yes possibly could be shoehorned into the hull, but that may be a later build. I just wanted to see if I could pull it off with the limited knowledge I have. One other thought I had was to extend the outlet of the jet further. Currently it sits just below the water surface. I might try to add a little weight to drop the stern down further. ▲
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π¬ Re: Lorelei.... 1st pond trial
11 months ago by π©πͺ RNinMunich (
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I'm with you Ramseyπ
Lotsa revs does not necessarily mean more thrust. Sometimes just the opposite. Cheers, Doug π ▲
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π¬ Re: Lorelei.... 1st pond trial
11 months ago by π©πͺ RNinMunich (
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Hmmm! Good luck with the 2200kV CJπ€
You may well get fireworks, but maybe not those that you are hoping for. But frankly I don't think that kV rating of the motor is your real problem here. OK you will get roughly 2.2 times the rpm using the same battery but I'm not sure that will help much. (BTW: You could also achieve almost the same effect by doubling the battery voltage on the 1000kV motor. You did not mention what voltage LiPo you are using!?) No! I believe that you have two basic design problems here. 1. You have applied a great jazzy offshore power boat type colour schemeπ but you actually have a relatively beamy hull more suited to a cruising type boat, with a roughly 3.5:1 length to beam ratio. Fast power boats and naval ships, e.g. destroyers, typically have l/b ratios of around 8 to 10. Reason: for the same power unit the higher the l/b ratio of the hull the faster the vessel can go. 2. The water jet! Here I admit I have no experience of water jets and do not know how their efficiency compares with a conventional prop. BUT! I think that your WJ is basically too small (15mm propπ€) and more revs may not produce more thrust and speed, but possibly just more cavitation and disturbance of the jet flow. Your boat is 23" you say. A few years ago I restored an Aerokits Sea Scout, built by my Dad in the early sixties. She is 24" LOA and 8.25" beam. I.e. l/b ratio 2.9. She has virtually the same hull form as your boat and is fitted with a Propdrive 2830 1000kV brushless running off a 3S LiPo driving a 30mm 3 blade conventional prop. And frankly I reckon she would run rings round your Lorelei in her present state. See attached video (U-toob link) of her sea trials or my Gallery post here- ![]() ![]() ▲
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π¬ Re: Lorelei.... 1st pond trial
11 months ago by πΊπΈ RamseyA (
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Looks great, all considered: scratch built; interested in your jet drive l believe you mentioned. Yeah, is a SPEED boat π€.
Me , I'm a TUG BOAT person; so I come from the Thrust, not so much RPM side of things. I'm learning π βΊ π thanks π€ much to this group π. ▲
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RNinMunich
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π¬ Re: Lorelei... Detail view of Water Jet install
1 year ago by πΊπΈ cjanik001 (
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Thanks all for the likes and comments so far.
JB, I scanned your blog several times to see which motor you ended up with, but maybe I missed it. I think 11K RPM is all this one will be able to handle. The unit has only one brass bearing at the prop end. In fact I had to replace the stock shaft coupler because it was drilled off center and had a bad vibration. Good thing I tried it out before securely mounting the motor, as it would probably have warped the plastic housing. I will be happy if the boat get on a plane with some decent speed, not looking for it to be a racing boat by any means. I will probably write a blog next week, as the hobby room is being transformed to a party room for the U.S. Memorial Holiday. Need to clean up the desk and put away the tools so the grandkids won't get into themπ. ▲
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taffy
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π¬ Re: Lorelei... Detail view of Water Jet install
1 year ago by π³πΏ jbkiwi (
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Looking good CJ, I'll be interested to see how it works out. I ended up with a 3000 kv in-runner on 3s and a different prop, (modified to reduce the clearance, on the 26mm jet), to get a bit more performance, as the boat is quite heavy (about 6lbs) Try and make the intake as smooth a flow as possible also, helps to reduce cavitation. Depends how much speed you want. I was just going for a bit of a scale look.
JB ▲
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taffy
cjanik001
stevedownunder
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π¬ Re: Lorelei
1 year ago by πΊπΈ cjanik001 (
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Hi HAKits,
Would like to see a video of it on the water, as well as more of the internals. Thanks ▲
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Remove Ads π¬ Re: Lorelei
1 year ago by π¬π§ HAKits (
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π¬ Re: Lorelei
1 year ago by πΊπΈ Peejay (
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Interesting project. Looking forward to progress reports!
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cjanik001
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