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-   -   ectension boxes (https://www.offshoreonly.com/forums/drives-lower-units/168011-ectension-boxes.html)

soak_it_n_cider 09-05-2007 07:24 PM

ectension boxes
 
Will extension boxes help with chine walk? I have a 1997Thompson torrent very rare boat this is the only one I have seen. The hull has no steps no notches traditional 24 degree v.
It has twin 454 blower motors 650 hp with bravo drives 1.5 ratio 26 pitch bravo one props. The boat will run 76-78 mph with no trim and be pretty stable engine rpm is about 5000once I start to bring the drives up in a 2-3 foot chop it will start to chine walk and I can't drive through it. But on flat water no waves what so ever I can bring the trim up motors will rev about 5450 and run 84-85 mph but any thing other than flat water it gets SCARY sorry for being long winded thanks in advance Jason

soak_it_n_cider 09-05-2007 07:34 PM

Here's apicture of the boathttp://a83.ac-images.myspacecdn.com/...66457082_m.jpg

Audiofn 09-05-2007 07:40 PM

Do you have external steering? Props turning in or out? What kind of props? Any hook in the bottom of the boat? Have you tried to move things like your batteries and stuff around to try and rebalance the boat? Tabs?

soak_it_n_cider 09-05-2007 07:57 PM

I have bravo one 26 pitch props turning in, tried turning them out makes it worse, no hydraulic steering yet, if extension boxes will help I would like to add the steering and the boxes at the same time. There is no hook on the bottom, batteries are as far forward as I can get them this boat come with 4 batteries so not many places to put them, yes I do have tabs no change, Jason

articfriends 09-06-2007 12:34 AM

Jason,how much play do you have in the drives and gimbals if you just grab them out of the water and wiggle everything side to side until you feel the slack take up out of the steering? If you have much then theres where your chinewalking is coming from,Smitty

2112 09-06-2007 12:51 AM

If you find your drives are solid, I would believe is is your basic hull design. I had a 24 Warlock that had to get into the mid 90s to get through the chine walking. I got there by big power and less trim.

Having said that, I always believed putting on an extension box AND placing a cavitation plate on the transom to mimic a notch would help immensely. I believe a good glass shop could also give you a pad bottom which could be sanded off if it was a bust.

soak_it_n_cider 09-06-2007 07:04 AM

I do have a little bit of slack about 1/4 inch I plan on adding steering throughout the winter and going through the gimbals I figured the chine walk was coming from the drives moving and the lack of hydraulic steering, I didn't know if extension boxes would be benificial

Carder 09-06-2007 12:59 PM

Jason, Couldn't help but notice last Sunday morning at 7:30 am, that you also didn't have silent choice.
Carder

soak_it_n_cider 09-06-2007 01:08 PM

sorry about that, had to pull the boat out of the water to get fuel no premium on the river, you run extension boxes correct have you compared your boat to another one without boxes and if so what do you think

Carder 09-06-2007 02:51 PM

Jason, my hull was meant to go 100+, so it doesn't have any cavitation issues even at 92 mph. The extension boxes were the new technology at the time (1999) to get more speed out of an existing engine/drive package. It does that. I go faster than other HP500's on single step Fountain hulls.
The next year, 2000, they redesigned the hull to a double step, and that increased the performance by 10%, same as the boxes did. I like my boxes, but I haven't seen many since the hulls were reconfigured. It sux there is no premium on the Bay. Carder


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