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Thread: Thoughts of adding strakes
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09-15-2014, 06:37 AM #1
Thoughts of adding strakes
Background,
This winter I intend to flip my 20' Glastron in order to refinish the bottom. Over the years it has accumulated many chips and developed blisters where it sites on the bunks.
A chip or two are letting water migrate into the hull which has been structurally rebuilt.
This boat is a straight V hull with 18 or 19° rise with 4 full length strakes. I have removed the hook or at least most all I could from the center portion of the running surface. This will be checked once the hull is flipped onto a cradle.
When I bought the boat it ran 47mph and with the work I have done it tops out at 62 now.
The engine will be receiving an Excel powerhead so if anything next year will again be a quicker runner.
My question,
I have been giving thought to adding a pair of strakes inboard of what is there. The existing inner strakes are 26 apart on their outer face.
What I do not have a feel for is what differences in handling, ride and performance would one expect from the added lift?
I am expecting a performance gain such as a pad offers but I do not have enough experience running different hulls to know what to expect.
I do not have an image of the bottom so this view from the back might be what I have now,
Regards,
Charlie North
If it ain't broke, modify it.
80 21' Superboat with Yamaha 225 Excel power
76 Glastron to be powered by a 6.2 L92 with surface drive
87 Glastron CVX20 Hull
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09-16-2014, 05:24 AM #2
DONT ADD MORE STRAKES JUST INCREASE THE WIDTH OF WHAT THERE ON THE 2 OUTER ONES
Double there width or even go to 2 and half times as wide , make then from wood and resin coat and screw in place to trial them and see if that's where your headed . don't increase the width any more than 6 to 8 feet forward of the transom as that's about how much of the hull length is carrying the hull weight at speed ! and if you go to far forward then makes a hard riding hull
Me I like wide strakes and there stability they offer rather than a ski plank down the middle so the hull falls one side or the other and end up chine walking !!Messing round with boats is fun !! the learning never stops ,even after more than 30 years there's always something new happening somewhere ! BUT somethings never change and some problems never go away and just keep reoccurring !!so moved into Composite Forensics , Now that something completely new !!
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09-16-2014, 05:43 AM #3
Outer ones, Interesting, my mind was on inner. Your thoughts will provide a very stable base and yes I do not want to build a narrow tricky to drive platform, nor a hard riding one.
The one bit of information I am missing on my boat are good pictures of how the hull rides at speed. I do not know if it is lifting above the outer strakes now or riding on them.
And this leads to how much hull is used when running 10 to 15 faster than it runs now.Regards,
Charlie North
If it ain't broke, modify it.
80 21' Superboat with Yamaha 225 Excel power
76 Glastron to be powered by a 6.2 L92 with surface drive
87 Glastron CVX20 Hull
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09-16-2014, 06:52 AM #4
I've had similar thoughts of extending my inner chines to the stern as GT hulls have them ending about 2ft before the transom. I would imagine full length inner chines on our hulls would be the closest to a pad without having a true pad.
My hull rides right where the inner chines end
Maybe it could cause more violent chine walk as the hull starts riding higher on the vee and ruducing the wetted surface on the added strakes???Last edited by CptBeav; 09-16-2014 at 07:02 AM.
"If it ain't broke, fix it till it is"
Glastron GT150 Johnson 120
Trophy 2159 OMC 3.0
14ft jon
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09-16-2014, 07:05 AM #5
A few years back I read about the inners on the 150 being extended back. To me that is logical in that it will give more lift further back which will flatten the hull at speed. The flatter hull should be more stable.
Regards,
Charlie North
If it ain't broke, modify it.
80 21' Superboat with Yamaha 225 Excel power
76 Glastron to be powered by a 6.2 L92 with surface drive
87 Glastron CVX20 Hull
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09-16-2014, 07:24 AM #6
Nothing works as well as a center pad. Glastron made a few 20ft Mod-VP boats way back in the early 80`s with a pad. The boats were very stable.
BTW, Make sure you change the tuner to one made for the Excel when you install the powerhead.
DB
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09-16-2014, 07:28 AM #7Screaming And Flying!
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Bottom is good, just add some more power......If anything widen all the existing strakes so the balance is still there. Remember though, the more wetted area, the more drag you must overcome. Once again, more HP needed.
83 V-King, 96 Mariner, 200 hp ff block 2.5 w/a 28p choppa
We gotta clean this liberal mess up, VOTE TRUMP TO MAGA!
Rebuild thread:
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09-16-2014, 07:33 AM #8
I look at the few pictures of the blue mod Vp boat longing for it to come to market. But I am sure that when it does I would not be able to fund it at the time.
I have the tuner sitting here, My desire was to get it in under my existing powerhead for this past season to see if the restrictive tuner is what caps the rpm to 5100. But last winter the engine stayed on the boat rather than being stored in the shop so I never got the chance to pull it apart.Regards,
Charlie North
If it ain't broke, modify it.
80 21' Superboat with Yamaha 225 Excel power
76 Glastron to be powered by a 6.2 L92 with surface drive
87 Glastron CVX20 Hull
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09-16-2014, 07:36 AM #9Regards,
Charlie North
If it ain't broke, modify it.
80 21' Superboat with Yamaha 225 Excel power
76 Glastron to be powered by a 6.2 L92 with surface drive
87 Glastron CVX20 Hull
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09-16-2014, 10:57 AM #10If I knew it was going to last this long I would have taken better care of it.
Chris
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09-16-2014, 11:22 AM #11
It defiantly is not what one would consider a fast hull, after all it is just a ski boat. But I think with a bit more lift it could be "almost fast"
I just do not want to loose the good characteristics such as the ride.Regards,
Charlie North
If it ain't broke, modify it.
80 21' Superboat with Yamaha 225 Excel power
76 Glastron to be powered by a 6.2 L92 with surface drive
87 Glastron CVX20 Hull
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09-16-2014, 11:23 AM #12Screaming And Flying!
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Going from a 150 to a 250+ hp motor should make it a diff boat. 60 mph w/150 hp is good as it is now. Same boat with 250 XS would perform well.
Last edited by XstreamVking; 09-21-2014 at 06:17 AM.
83 V-King, 96 Mariner, 200 hp ff block 2.5 w/a 28p choppa
We gotta clean this liberal mess up, VOTE TRUMP TO MAGA!
Rebuild thread:
http://www.screamandfly.com/showthre...-it&highlight=
http://www.screamandfly.com/showthre...cs.&highlight=
Videos
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09-16-2014, 11:36 AM #13
My 150 has the 34mm carbs and horizontal reeds. The porting is the same as a 1990 200 which is claimed to put out 210ish. Since I have the restrictive tuner still I expect that keeps me capped well less than that.
The Excel will be quite noticeable from this level especially where the proper tuner will let it spin up a bunch more.
Part of me says to just clean up the bottom and not modify it at this time. But then that part of me that modifies most everything.
This thread is good for the thought patterns.Regards,
Charlie North
If it ain't broke, modify it.
80 21' Superboat with Yamaha 225 Excel power
76 Glastron to be powered by a 6.2 L92 with surface drive
87 Glastron CVX20 Hull
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09-16-2014, 12:42 PM #14
My uneducated opinion would be to make a pad, but it does take some ability to drive it on the pad! Less boat in the water, time to fly!!
why ask me ?
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09-20-2014, 06:46 PM #15
I have some more information for my project, This afternoon I got a chance to get on the water with a friend being able to snap some pics.
These two pics are of the boat running the high side of 61mph, all she wants to do at this time.
Clearly no point in working above the inner strakes which the hull is planted on.
Critique?Regards,
Charlie North
If it ain't broke, modify it.
80 21' Superboat with Yamaha 225 Excel power
76 Glastron to be powered by a 6.2 L92 with surface drive
87 Glastron CVX20 Hull