way2fast

I have got a 25ft offshore V hull. just bought a pair of Yamaha betx 300hp. what sort of props should I be running and x dimension drive height etc.
my area is almost always sloppy and short sharp chop. Want a good compromise of top end and holeshot.
are vertical trim (jack plates) a good idea?
how are the 4.2L yamahas regarded you see them a bit on the centre consoles but mercury still seems the choice??
thanks all

johnmiffco

what hull do u have,,,,,does it have a notched transom and if so how much
if use jack plates need the offset amount as distance from bottom to motors
helps to give u an x dimension
u cannot go to surface as u don't have low water pu on gearcases
so need total offset amount for a starting point
the 4 stroke are tad heavy on a 25' offshore hull for rough
may end up adding some bow ballast to help ride

turbo rr

iTrader: (3)

What 300 yamahas do you have? Are they hpdi's or 4 strokes? What length midsections? Do you have a bracket or not? Plus what he said about the hull, What hull do you have? Because most 25' boats cant take the weight of 2 300's.

way2fast

it is an australian designed hull called a jenks craft. 25 feet long. they raced them back in the 70's so quite an interesting pedigree. not many people know of them on this website.

it does not have a notched transom. the engines are not yet mounted so not offsets yet. hence my thread
they are the new 4.2L 4 stroke 6's. w 25 inch mid section. the boat does have an actual custom matched hull extension for the outboards rather than an bracket

this guy posted some pictures of the boat here so you can get an idea of it..
this was before I got it. see pics of it here before i got my hands on it.

http://www.offshoreonly.com/forums/g...tery-boat.html

rak rua

Early 70's hull built by Norm Jenkins. Pretty strong guess it was flopped from something American. John Haines had Haines Formula on the go which was the American Formula built under license. The two raced competitively and also Mustang 24' appeared on the market. Another flop, this time, I think it was Graeme 'Noddy' Williams.

I always thought the Mustang and Jenkscraft were the same hull but different deck. Both are awesome rough water boats and there's always a handful for sale in Aus but either in rotten condition or beautifully done up and chasing a fortune. $$$$.

Sorry I'm not much help but whenever I read about Jenkscraft or the old Mustangs I get excited. It's the Aussie equivalent of a Magnum project.

RR

rak rua

Here's one with twin 275 Zukes for 50k AUD in West Australia

[ATTACH=CONFIG]561366[/ATTACH]

[ATTACH=CONFIG]561367[/ATTACH]

And another with Yammies at Pier 35 Victoria for 49k

[ATTACH=CONFIG]561368[/ATTACH]

[ATTACH=CONFIG]561369[/ATTACH]

way2fast

thats the one.
im still wondering as per my original question whats the best way to set it up.
it is plenty of power for a hull of this size so I want to get the propping and heights right.
otherwise it could be unsafe