Re: Invader

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screwit
Posts: 1009
Joined: 09 Apr 2010, 21:29
Location: Stratford vic

Re: Invader

Postby screwit » 07 Sep 2020, 19:46

A test run today .
Steering is better than it was but did have a 3 blade prop on that tended to roll the boat a bit.
3200 RPM = 42 mph
5000 RPM = 60 mph .
I didn't push it past that because of the roll and water was a bit flat . I think it would still run to 6000 with this prop .
Had to be towed back after over heating only to find the water pump impeller was still in one peice but the shaft turning inside.
She did get prity hot though before l noticed the water not exciting the boat out the side .

Wildwoody1
Posts: 145
Joined: 24 Dec 2013, 18:47

Re: Re: Invader

Postby Wildwoody1 » 08 Sep 2020, 10:10

Sounds good , hopefully no damage. 12 mph per 1000 rpm an efficient prop with not too much Slip.

screwit
Posts: 1009
Joined: 09 Apr 2010, 21:29
Location: Stratford vic

Re: Re: Invader

Postby screwit » 17 Sep 2020, 07:28

Next bit of testing might involve a strip off timber under the left bearer about 1 mtr's up from the transom to push the hull down and see if it helps the roll at speed .
Any thoughts ?

RightyO
Posts: 187
Joined: 23 Oct 2012, 19:14

Re: Invader

Postby RightyO » 17 Sep 2020, 14:45

Interesting idea Ross , B Pee feels like the nose is dipping at high speed at about 6200RPM .I tried a larger blade prop and it made it worse but if you see pics of the boat racing the seem to have a jockey right behind the driver i assume to counter the pitch . The box in it is close to 1to1 ratio and i have been thinking that different gearing with a smaller prop would solve it .
ken

Wildwoody1
Posts: 145
Joined: 24 Dec 2013, 18:47

Re: Re: Invader

Postby Wildwoody1 » 17 Sep 2020, 15:29

If by bigger you mean a larger diameter forget it.Will raise transom and twist the Hull about more. Your view on changing gearing and using a smaller diameter Prop should see changes. About 11 1/2 should be max diam , 15 1/2 pitch worked well on 300 ci Boats back in the day. Gears changed to match Horsepower. Here is a Pic I have:
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WoodRay
Posts: 482
Joined: 12 Feb 2014, 15:19

Re: Invader

Postby WoodRay » 17 Sep 2020, 18:15

You need a small winged keel under it!

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Darren
Posts: 531
Joined: 08 Mar 2009, 21:18
Location: Mornington Peninsula VIC

Re: Re: Invader

Postby Darren » 18 Sep 2020, 14:32

Have to agree with the Wild woody, Mine always handled OK but when Steve Moritz took diameter out of mine, plus cut the actual blade area.
The difference in straight handling was substantial, and with the little 302, and speed was not lost. 71.6mph at 5500
I think the would be more pronounced with a narrower beam and your greater horsepower
My 2 bobs
Darren

Wildwoody1
Posts: 145
Joined: 24 Dec 2013, 18:47

Re: Re: Invader

Postby Wildwoody1 » 18 Sep 2020, 17:20

Some of the 300 ci Factory Boats out of Gippsland in early 1970,s ran RECORD Props around 11 x 15 to 16 pitches. Bigger Engines called for different gears.

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Darren
Posts: 531
Joined: 08 Mar 2009, 21:18
Location: Mornington Peninsula VIC

Re: Re: Invader

Postby Darren » 19 Sep 2020, 10:09

Yes gears are another consideration, mines probably a bit tall for the skiff, hence the smaller diameter prop. In my case I gave Steve a choice of 3 props to start with, and he went for the one I least expected to my eye, and significantly cut it down as I mentioned previously. He told me he chose it for the variable pitch. I have to admit props are a "dark art" but overall from my experience if the prop is too large in diameter it will pull the boat over at higher revs


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