samin
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Posts posted by samin
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an old thread
but have been researching prop specs
as previously stated
the yamaha 8hp 2-stroke is a high power, low weight, popular choice for 8.5mt multis
it comes standard with a large pitch 10'? all white prop designed to get light dinghies planning
there are also 2 lower "geared" "dual thrust" options for boats heavier than a dinghy that will never reach those speeds
the black hubed 9" x 7"N, for light weight multis (9 inch diameter with 7 inch pitch)
(cast into the prop alloy)
and the black hubed 9" x 5"N for heavier boats with heavy keels
the black hub is "dual-thrust" in yamaha speak, which means in-hub exhaust so the blades are less likely to cavitate in reverse and lose bite.............most light tinnys/inflatables etc don't reverse much so don't need this exhaust gas diversion
solas also make 5 props for the yami 8hp 2 stroke, the 4 bladed versions with in-hub exhaust probably the best choice for multis
yachts heavier than 900kg probably want more power AND lower gearing
for them the 9.9hp was made with lower reduction gearing to prop (planing speeds not needed)
AND a range of dual thrust props for differing boat weights
..............
cavitation protection in swells
small multis with a single outboard mounted centrally seem better with the long shaft engines as the hulls can lift the prop out in swells + waves
yamaha make just the 1 long shaft option but tohatsu make a long and an extra long
as Greg has on Mysterex
but even the standard long shaft yamaha can still get lifted clear enough for the engine to scream as the prop half spins in air.......one way to help prevent this is to bolt an aftermarket hydrofoil to the engine's small anti-cavitation plate just above the prop
http://www.trademe.co.nz/motors/boats-marine/parts-accessories/outboards/auction-1168791372.htm
the barnys fitted 1 to capricorn's 8hp 2-stroke yami
and it seems to be working well
they are just a cut + bent bit of alloy sheet so am going to knock up another out of some spare ally checker-plate for the spare engine
also outboard mounts that have multiple down positions help to keep the prop from spinning free
capricorn is set so the 2nd from bottom hole for motoring off the mooring, with sails already raised
but need the max bottom setting for motoring in, as when head to wind to drop sails, my weight moving from stern to bow, can lift the prop clear from the 2nd from bottom position
I need a new prop for my boat and this post pretty much summed up the information I needed thanks. Also all the other contributions to this thread, excellent thanks. I will post my results soon
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Do you remember what wind direction it was? I would have thought it would be sheltered
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I have been up on a runabout and it seemed like taking the tri would be no drama but I wasn't paying much attention to cable etc so guess I'm just checking the heights etc are ok... Also how much tide/current is there and is ok to anchor near riverhead pub? I'm not keen on putting the boat on the jetty
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Did this ever happen? I'm planning on taking my wife and kids for a cruise to Riverhead at some stage.
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I did the beams and cabinside with International Perfection and it was super easy to get at good finish and its very hard durable paint. The biggest challenge is keeping the dust off it as it stays tacky for ages.
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not sure if this counts as old but it seems a long time ago! Stealth Mission, 2010, (nephew inside)
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Im keen. When?
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Well I get the vibe protesting is frown'd on with some members the multihull club. playing chicken is what they do!
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I asked my crew pull the red flag as I called protest but they refused
Hmmm - I'd have just as much of a problem with that
So after speaking to Tim tonight I apologize for calling him a cheat. Seems he made a mistake that's all.
What would you do. Anthony? Bend over and take
It???
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No it was great fun other than the port starboard with timber dog
I asked my crew pull the red flag as I called protest but they refused saying different division but given the fact tim cant even apologize for being a blatant cheat and it happens frequently im pretty dark. Didn't only effect me also caused me to majorly luff the boat above me
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Next time you forget to give way when your on port I will drive my bus straight thru your sh*t box tim.
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wow what a amazing finish, nice work. How much they weigh now?
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I would do it the same as bmw oracle, if you wanna be clever fade it from green into grey at the bow like their old keelboat faded from black to white otherwise the lazy option is like the DOG Tri just cut off with and angled line, looked fine to me.
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Hows progress on the port float?
is it easier to fair the hull before putting the fittings on, (i.e. tramp tracks) then grinding the bog off, secondary bond, then re-fair the areas?
or put all the fittings on then try bog and sand around them in one hit?
or is it "6" one way 1/2 doz the other?
so far iv done it one way on the main hull and the other on the beams, both ways seem a pain in the ass....
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im going to build my boat, which is what you should be doing.
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Rob's boat won't be here by Xmas - hopefully around end of Feb, otherwise yes he could race in our rum race.
I was referring to the NZMHYC refusing an entry which I found a bit disappointing.
Regardless of any clubs accepting entries or not, I would hope that, after all the spouting off here, if Rob shows up with his boat and challenges anyone in Auckland to race him on a triangular course at a certain time and date. There would be a few people who would be honor bound to back-up their statements and take him on??
Takers?
Yes Dean I will be keen, I haven't forgotten my challenge to Rob (or any Proa owner/designer for that matter). Its just been so long since I offered the challenge (and still no proa) that the boat I had is sold and the new boat is being built, but hopefully the owners of Capricorn would let me come out with them for a little race with the Proa?
Unfortunately theres still no Proa thats actually racing?
And Dave stop going on about the NZMYC banning the tacking proa (with no CAT 3) back in the 80's its time to move on!
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Ok, so I said it wrong.
Here is my point though.
Our sailing displacement is 1450 kg, so the buoyancy of our new ama is 240%? (Being 3500/1450 x 100)
When I bought Wolfy it was claimed it had 200% amas, but when you flew the main hull, the gunwhale of the ama was virtually level with the water, and there was very little reserve.
I think a lot of people state there ama buoyancy % using the weight of the bare boat, not the Sailing Displacement, including alll crew and all additional gear on board?
so if my new ama is 240% then are Lucifers and Sam's new boats amas really 350% ?
My sailing displacement is only a few hundred kilos heavier than Lucifer, so wouldn't those 8.5 amas need to have 4400 kg of buoyancy to be 350%, I know they are big but where is all the extra volume? they are giving away a decent amount of length, and our ama is still 900mm deep by 600mm wide.
Or is this not how you work it out ?
Yes Tim some people use the boats weight and some people use the sailing weight inc crew, which is prob a better way of calculating it,
so we should be 900kg(inc cat 5 safety gear) +50kg (sails) + 300kg (crew and lunch/beer) so 3500 / 1250 = 280% floats, not 350% as I said before.
Even this sort of ratio theres bugger all freeboard on the floats when the main hulls flying high especially when sailing with 4 not 3 and wet sails etc.
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I told Gary a while back id give him a bottle of rum if they were under 100kg each...
Can we be sure this is not your way of saving your handicap and they actually weigh 60kg???
How much were the old ones?
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I had a look at the new float yesterday, very nice design and build quality.
Perfect upgrade for the Wolf to make it slay some more cats.
Keep wondering to myself if the smaller foil assisted floats would have been better for my new boat but I dont think their would be enough horsepower to drive the foils in a wide range of conditions within the 8.5 rule so still happy with the monster 350% floats like Lucifer...
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As I said I'm not actually asking about the financial agreement, the number of hours is irrelevant without knowing what the hourly rate is.
As I said I was asking to get some sort of comparison of your project of longer floats with professional boat builders to our project being worked on by a couple of amateurs.
If you don't want people asking you questions about your project why bother putting photos on?
Just forget I asked, Good luck with the launch date and keep up the good work
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No sam.
Gary runs a business building boats.
I have made an arrangement with Gary to build me two amas.
He has agreed to that for a certain price.
It is costing me what I expected and it is taking him the time that we both expected.
It is not the place to discuss private arrangements online.
Your estimate is a long long way over the top.
BTW our estimated ama weight is 75 kg
I wasnt asking about the financial arrangements just curious to see how long it takes a couple of pros to build some carbon floats.
Me and George were hoping to take 600 hours but it was more like 800 to do our tortured ply floats with a bit more fairing and painting yet.
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at this stage and I'm hoping to have both the amas ready to join onto the beams in 6 weeks time from now. So far the build has taken 9 weeks.
Can I safely assume between you two and occasional friends helping you would be averaging 75 hours a week?
which would mean you have done 675 hours until now and the total project will be around 1100 hours?
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a few questions if you dont mind?
1. How are you going to bail the water from under the shear web?
2. have you managed to figure out a clever way of getting air circulating to prevent dampness inside the hulls?
3. how many man hours was the target for 2x completly finished floats (attached to beams) and how many man hours have you taken to get to the stage they are today?
4. How much glue have you allowed for joining the two halves in your weight study?
GBE outboard motor
in MarineTalk
Posted
https://www.trademe.co.nz/Browse/Listing.aspx?id=1489972768&ed=true
Im selling my 2006 8hp Yamaha if anyone needs one.