TNT w/40 hp merc and WRONG prop

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Craig_Bay
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Joined: Wed Aug 22, 2007 7:52 am

Postby Craig_Bay » Thu Jul 03, 2008 11:35 am

I did end up jacking it up a tad, but the prop just cavitates when trying to get up on plane with any decent trim. It may be because its a thin bladed brass two blade. I think ill try a 3 blade cupped 17p one of these days and see what happens. I feel like the boat/motor combo has so much more to give, but I cant trim it to get out of the water and run quickly with jst one trim setting. I was wondering if i could rig a manual trim on the go with a car jack against the transom or something along those lines. haha.

Scott
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Postby Scott » Mon Jul 14, 2008 11:24 pm

A Higher pitched prop and cupping would be necessary for that matter. A step up/down to aluminum would be a good start. Re-hubbing the newer or used prop to fit your current motor is under $100, some under $50 in some places.

About your Dr. Seuss way of putting it, did you happen to mean getting electric/hydraulic trim for your outboard? You can buy them...but it would be awesome to have made your own.
Thun.der.bolt
ˈTHəndərˌbōlt

A flash of lightning with a simultaneous crash of thunder.

An ignition system of early Mercury outboards that not only is a nightmare to diagnose but also improves a marine mechanics competency.

Craig_Bay
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Joined: Wed Aug 22, 2007 7:52 am

Postby Craig_Bay » Fri Aug 22, 2008 3:50 pm

What i ended up doing was just buying some smart tabs, in hopes that they'll keep the bow down and allow me to get on plane with the higher trim angles. Havnt installed them yet, but will get around to it this week. Does anyone know if an aluminum prop would end up turning much more rpm then a brass? Good call on the rehubbing scott. I think ill see if i cant get a 17 or 18p prop and get it rehubbed.

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Andrew N
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Location: Ontario, Canada

Postby Andrew N » Tue Aug 26, 2008 9:40 am

Hey, Craig_bay, read my article "performance tip for TNT owners" in the speed/performance archive. It may be of help.

Craig_Bay
Posts: 20
Joined: Wed Aug 22, 2007 7:52 am

Re: TNT w/40 hp merc and WRONG prop

Postby Craig_Bay » Thu Jul 30, 2009 9:13 pm

Thought id give a brief update on my boat. Ended up buying a CMC PT35 power trim unit this summer for the boat. I wish id purchased the pt130 instead in retrospect as i have a 50hp motor and the pt35 is recommended for 35hp and under (imagine that). Anyway, it seems to be holding for the moment, though ive seen pictures of broken welds with a modern 50hp (165 lb vs my 150lb) Im hoping that if im careful with it and use it in calm water it will stay together. Anyway, this thing has made a world of difference. Im running around 48mph now trimmed out and i cant cruise around all day with no proposing with it trimmed down. Definitely a well spent 500$. Installed those auto trim tabs for a bit and they worked just as advertised, however they hurt the speed a tad. Definitely recommend them if you're not concerned about a couple mph. Anyway, going to try to post a video one of these days so you can all expierience the terror of an 11ft boat at 50mph. :p Take it easy guys.

upspirate

Re: TNT w/40 hp merc and WRONG prop

Postby upspirate » Fri Jul 31, 2009 7:12 am

Glad it worked out.

What is the weight of that T&T unit?

Craig_Bay
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Joined: Wed Aug 22, 2007 7:52 am

Re: TNT w/40 hp merc and WRONG prop

Postby Craig_Bay » Fri Jul 31, 2009 4:50 pm

Hey again. I believe its about 20lb. Weight was the reason i went for the pt35 rather then the 130, as i believe the 130 to be significantly heavier. Im amazed at the versatility of this hull. Its obviously not meant for this much power/speed, but with a bit of reinforcement and some caution, it handles it incredibly well. Almost nil proposing unless im traveling very slowly, and if i over trim it, the prop just cavitates. . Granted, i wouldn't want to hit any sort of wave at full juice trimmed out, but thats where the caution comes in. I hope someday to be able to build a different glen-l boat such as the stilletto or tunnel king. One day...

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dabren
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Re: TNT w/40 hp merc and WRONG prop

Postby dabren » Fri Jul 31, 2009 8:04 pm

Thanks Craig_Bay, like my drive to get my TNT finished wasn't already enough - now your comment "experience the terror of an 11ft boat at 50mph" just put everything else in my life second!

Dan

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Andrew N
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Location: Ontario, Canada

Re: TNT w/40 hp merc and WRONG prop

Postby Andrew N » Thu Aug 13, 2009 5:00 pm

If anybody could make a video of this 50hp machine in action, I would love to see it.


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