DIY Boat Propeller – Part 10 – Tested at 600 rpm

this is a variable pitch control propeller system 
so it's actually made up of two shafts this one   works in and out and both of them spin so what 
happens is this inside shaft can move three   inches in and out and as it does this pin has 
a block that rides on it and the block slides   in a groove that's in the base of each propeller 
so as it moves in and out the propeller changes   this angle of attack or its pitch pitch like 
this on a motor boat it would just be spinning   around or feathered it wouldn't be pushing any 
water this direction or that direction for our   sailboat this is considered feathered because as 
we sail forward water passes by the propeller and   there's not a lot of drag but the cool thing is we 
can change this to any desired pitch so we can mix   engine power with sail power in other words we 
can be sailing along at four knots put a little   bit of engine power into it pitch the blades 
appropriately and pick up another two knots   and we've cast two sets of these propeller blades 
this set though i haven't yet ground down i got   a nice sharp edge originally i didn't have a 
shroud on the boat but then i added a shroud   and so i've cut these so that they fit just 
inside that shroud now this round piece of   metal back here that wraps around where the prop 
goes is our shroud some people refer to them as   court nozzles but this really isn't a core nozzle 
a cord nozzle would have a an aircraft wing shape   design to it here and it works a lot like an 
aircraft wing it helps build a low pressure   here and accelerates the water before it even 
gets to the propeller they work great and better   than a shroud but they also have more drag so when 
we're just sailing this will be a little bit more   efficient than a quartz nozzle and we might modify 
it later on it would be really interesting to see   the contrast between a shroud and a court nozzle 
you know given everything else remains the same   inside the boat is where this gadget down here 
sits that's our 100 dead variable pitch control   unit drive shaft attaches to this end propeller 
shaft comes through the shaft log attaches there   a push pull cable will attach to there and it 
changes where that brass fitting down there rides   along and that changes to where oil is either put 
on this side or this side of a big piston that's   right there and when that piston moves that inside 
shaft there moves and that changes the propeller   and the hydraulic oil that will be supplied to 
it will just come off the power steering pump on   the engine so whenever the engine's running 
the hydrostat will have oil supplied to it   so the first thing i need to do is put that 
shaft in the boat and set this set in there   mark them off and trim them down appropriately 
take the seal off i'm going to push out ah cutlass bearing and the next thing to go in is 
the cutlass bearing it's just a brass tube with uh   rubber on it it's got grooves in the rubber 
and that's where water can go through because   it's water lubricated and the water will 
actually flow back through and fill the whole   shaft log yeah it's going to take a little bit 
of force but that's okay what the water will do   is it'll flood the whole shaft log but there's a 
seal at the other end that stops flooding the boat   fresh coat of paint in there so if it's too tight   i'll have to take it back out 
and sand down some of the paint no too much friction so i get to use my 
cutlass bearing puller before i ever imagined   i would and one of my neighbors little girls 
brought me a cupcake merry christmas to y'all yeah i think was just too much for it gummed it up that's much better there we go yeah okay that's good enough all right 
that was pretty easy gracias amigo   no get us a fee here we go it's cold out this 
morning christmas day merry christmas everybody   not gonna have to take off much just a little 
bit that's a little too close right there   a little shake or a bump in the flange 
and it'll strike it i don't want that i've got two sets of these blades those 
i know fit so i'm just going to make sure   that these are actually no taller than those be 
careful handling them without gloves the edges   here are really sharp well i guess they're all 
within a sixteenth of an inch no more than that   now the goal is to get them balanced and and 
we've talked a lot about that uh the first step   is just a way of see where we're 
starting fourteen thousand and 544 grams so more yeah great so you ready for tacos man 
i'm getting hungry over here   i didn't think i'd get ever get 
hungry again after yesterday   yeah i pigged out i probably ought to put some 
trying to get my propeller system oh there it goes   you know you start cussing at something and it 
just all sudden works for you i got my pellet i'm   gonna balance the propeller today yeah some guy 
gave me this comment that i should spin it with   a drill and i just thought that was the nuttiest 
thing in the world and the more i thought about   it the more i kind of like the idea so i'm gonna 
spin the prop with a drill here a little while   that's walking down the 
beam oh it's gonna come off the whole propeller shaft and the 
prop i gotta figure out a way of   getting it not to walk down the shaft though actually come over half tacos okay okay all right yeah there's a little 
bit of wobble here but not much it's starting to wobble that's working fine it's not moving 
so this sand starts to rock back and   forth but it hardly has anything on 
it i think we shim it a little bit all right i think that's about 100 rpm i 
don't know what we're supposed to see is   it supposed to like shake apart more or i 
mean because it's sitting on the stand here   and it's not like the most solidly based thing the 
only thing i notice is it clicks one blade clicks there you hear it i heard it yeah 
so one of them is terribly tight that one there that was loose this is my second 
set this is my that was a little loose too your   spares yeah yeah that's the only one that's 
really snug they're just not greased but they   have just wd-40 on okay this is this is stable 
up here now i don't know that shim underneath it go for yep lunch oh lovely stuff you're going to pack all that 
fuel aggression anyway yeah okay all right that was easy yeah oh yeah grease helps a lot my ex-wife 
taught me that what use plenty of lube don't you have one of them rpm 
thingies i do let me see if i find it   oh it's even got a little laser light you see wow that's 95 already 95 rpm 108 yeah i 
bet we had it up to a few hundred last time oh man that is flying now 210 213.

Yeah there's a bit of a wobble right there if i throw it down a little bit 
i can just get wobble out of it   the question is how do we tell 
why it's wobbling you know 200 there's no wobble going up i wonder if the wobble 
will go out of it at a higher rpm   you think it would get more and 
more pronounced the faster it goes   it doesn't look like it's getting any 
worse in fact it looks smoother now this back one's got a little more wobble in 
it now no i don't think the shaft has been i   think it's just out of balance a little bit it's 
wobbling hold on take it on up now remember if   it comes out it's going to hit the dirt 
and it's going to fly off that direction   now this definitely has more 
wobble on the backside here and i think that's because the stand posts are so well my question is if it was if 
we were going to try and balance it   how would we know which blade to add weight 
to or take weight off of i mean with we   just i think we just have to experiment but i 
don't think that's enough wobble to sneeze at   these things are just sitting on dirt and boards 
so they're springy as hell i mean look at that i   can shake it around by just putting five pounds 
on it we moved these stands close further apart well there's no weight on this stand back 
here hardly at all right it's only most of   the weights on that forward all the 
wobble is right back here it's not   up there it kind of started up there 
and then it came back this direction so i don't know i think if i took 
lead bars and weighted that down more   i'll [ __ ] them on the frames yeah that's 
where it was taking it last time wasn't it   you can see a little bit of it 
not much dirty there's some wobble maybe this is what it feels like now the bearings are sealed 
they're probably all right can't wait it's consistent i mean it 
starts rocking and then it stays there   get about 230 to 240 and it's bouncing all right 
one's down here this is our second set of blades   this one's out by a hundred grams on weight 
so we're going to see what the difference is   try to wiggle man there it goes 
yeah that helped a lot okay you ready aren't you well 
ready now oh how about now oh no okay ready to rock and roll we 
tore the last one apart at 420 rpm   so we'll see if this holds together and this 
blade sets a hundred grams difference between   the blades the last one was only 24 grams so 
we'll get a very non-scientific measurement   here but we'll see how bad it shakes more or less 
i guess this is going to shake more grab the meter oh yeah queens that's really not taking any 
more than the last one isn't it 2 30.

Yeah   that's taking more it is sticking on 235 
248 242 it looks like it's smoothed out look at that look how smooth it's 
running down 30 50 360 360 80. 430 440 50. 4.90 500. five forty five 
fifty five sixty five seventy   five ninety five six hundred that's our max all 
right the grill's getting hot i'm coming off slow 6 30. all right there's three right 
in the house rotating with six   five eighty five seventy five sixty 
that's fantastic still going over 500 i think it has to do with the residence resonance 
residence yeah i think it's a residence problem   yeah let's stop it 240.

Well i don't think 100 grams is a big 
deal anymore yeah i feel real good about   that well no i mean i wouldn't do anything 
because there's only 123 grain grams right   okay just to give you an idea of how much 124 
grams is that's stainless steel stuff 122 grams   124 grams between the three blades i could take 
that off right out here on the edge if i wanted to   but i don't know where they're not balanced 
that's the other thing is we're not finding   center of gravity and this to me when you 
spend it if the weights out here on the end   and all this weight's in here close that's 
going to throw it off because this has more   pull force right because it's your weight's 
further out yeah yeah yeah the centrifugal   force would mess it up so i don't just need to 
get them in the right weight if i was going to   get them better i need to get them with the 
center of gravity in the same spot right   that's so smooth that's that's smoother than 
the other one was yeah and this is why this is   my first set yeah not my second set you 
know i i could i think what we do is we   put it in the boat we mess with it we have a 
vibration and then we can take them back off   while we're in the water it's no big deal and 
we i don't think it's worth messing with now   i only have one set of these square 
little blocks and it's just the kind   of thing you could drop into the drink 
when you're changing out a propeller blade   in the mississippi so i'm gonna get 
measurements off before it goes in   and draw up some just so i can make some spares 
now i'm not great at cat i just have functional   skills but i can draw these pieces up and 
then we can machine them out on the cnc and   we even did that to design the prop i started 
with mathematical formulas to give us the   degree of offset of these various chords and 
then we put a skin over that and that becomes the   pattern that we cast from so if you want to see 
videos on the making of these propellers uh i got   a whole series of them and most of the information 
is in a great book called uh propeller handbook by   dave ger and a great book for how to calculate 
all this stuff it even has a section here on   uh variable pitch control propellers so you 
ever want to know anything there's a book on it that may be the final installation 
so i'm going to jam it full grease   it goes oh yeah that's a nice sound it 
is still bizarre to see it floating yeah   sitting up in the air like that okay that's 
it next video we'll hook it up inside the boat   so fortunately it looks like we don't have to do 
anything further to balance our blades but if we   did or if we find that it's got too much vibration 
on the water there's some things that we can do   and one of them is to suspend the blade like this 
with a clamp but we'd want to put a real sharp   point on the clamp on this side and this side and 
that would give the blade the ability to find its   balance on those points then we get a spirit 
level and we put a line straight down the blade   that's perfectly vertical it's orientation and 
weight this direction then we unclamp the blade change its orientation about 90 degrees out 
and we draw another line straight down the   blade vertically where those two lines cross 
that's center of gravity and what we'd be after   is we'd want to get the center of gravity for 
each blade in the same spot and so by taking   some measurements we could see okay this center 
of gravity is much higher up than this center of   gravity so if we take some weight off the bottom 
of this blade that center gravity will move up and   if we got them all matched perfectly they'd be 
much better balanced so it's not just a matter   of their overall weight it's also a matter of 
where that weight is actually located on the blade   and as we saw in the cad drawings each of these 
blades is made up of a series of airfoils that   skinned over and if those air foils are a little 
different between one blade and the next then   the performance of the blade might be a little 
different it could be pulling a little harder or a   little less so that could cause a balance problem 
it's not likely because they're all good castings   from the same pattern but it could be an issue and 
if it comes down to that we can put it over on the   cnc machine and have it probe the whole surface of 
this and get a mathematical plotting of this blade   do the next blade compare the two sets numbers 
it'll tell you where this blades foil is a little   bit different than this blade then you find 
the heavier of the two blades and you grind   it down a little bit until they're perfect 
in truth i've seen propeller blades that were   plates of steel welded onto solid steel shafts 
and they were working okay so you don't have   to have everything down to spacex technology a 
lot of the in between stages will work just fine   so that's it the blades on what did you make 
today send us your photos and remember our travel   to the port date is august 12th and our launch 
date is august 21st come join us for a tragedy say but i will show all of you   the past is what i know the 
future is where i'll show yes say goodbye to what i used to know how fast 
time will come and go but i will show all of you the best is what i know the future is you

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