20ft SeaCraft With Twin V4's??? Just Thinking OL..
 

Anyone tried this?? Of course finding a 20ft and rebuilding/widening the transom to fit twins would be the first thing. Go with 25" engines and raise the transom to 27-28" in the center would clear up allot of the wash over... The question is...is there 60mph in those hulls. Will they get up on the steps and run?

Re: 20ft SeaCraft With Twin V4's??? Just Thinking OL..
 

Here ya go
http://classicseacraft.com/Archives%20Page%202.htm

My 20MA did 54mph with a 200 Yam Pro-V. You could
feel the bow lift after 50. 60 shouln't be a problem
with twins.

Re: 20ft SeaCraft With Twin V4's??? Just Thinking OL..
 

Thats one for www.screamandfly.com. I would think yes only because I've talked to the second owner of the Seavette when there we're 2 235's on it and it did in the 70's.

If Hermco would make a bracket for it I am sure the hull would take it. I would be more confident having that buoyancy for the weight of the motors for that 7' beam.

Re: 20ft SeaCraft With Twin V4's??? Just Thinking OL..
 

dunk ther was a 20 with twin merc2.5s on it down in the keys a few years ago. It sat real low of course and i saw it listed in the boattrader about a year ago. also in the potter years they would factory rig twin 70 hp hope this helps

Re: 20ft SeaCraft With Twin V4's??? Just Thinking
 

The seafari I have listed for sale. Had twin 50's when we got it but as I recall when we removed them in the early 80's they we not that big. Nothing compared to the size/weight of v4's. There is sill enough room although. I would think it would work out.

Re: 20ft SeaCraft With Twin V4's??? Just Thinking OL..
 

Now we're talking... I don't know how long ago you are talking about, but when I was living in the Keys in the late 80's there was a 23 in Islamorada with a pair of 2.5 Bridgeport Offshore 260's. I was running one of the headboats for Robbie at Holiday Isle on the night trips. I was coming up Rt1 just at the end of Lower Matecumbe at the Lignumvitae Key channel where it runs from Robbie's up to Papa Joes along RT1. These two guy's had just run the wheel ditch up behind Matecumbe and were lining up to run up to Papa Joes. I was pacing them, speedometer in the truck was reading 80mph and that 23 Seacraft was walking away from me.
You have to see that boat run to believe it. I never did see that boat again. I'm not sure if he was local or not.

I've seen some wild rigs built once you put USCG regs behind you.. Even a 75mph+ 20ft Whaler Outrage with a pair of 175 Evinrude Ficht's on it.

Finster..as you guy's get to know me you'll find that I'm dead set against bracketed outboards. Unless the boat was designed from the mold up to handle the engine(S) 30" behind the hull most don't run the way they should. I think it's an especially bad idea on seacrafts because you are putting the best part of the wave cutting deep vee in the air where it won't do you any good. Yes, patching up an old stern drive with a bracket for an outboard is good way to save the boat because you are removing a 1000lbs of sterndrive and engine. Boats like that were designed to handle the weight on the transom. My next rule is nothing under 23ft get's a bracket. Moving the engine 30" behind a boat like 20ft Seacraft that was never designed for it, I think is foolish just to gain a little space in the rear of the boat. There's too much "Notched Transom" fear running rampent on the internet. The biggest reason boats sink from water over the transom is not keeping your deck access plates water tight. 90% of the boats I survey I find bad orings or broken access plates that will let water flow into the bilge.

Re: 20ft SeaCraft With Twin V4's??? Just Thinking
 

Dunk
In Ft Lauderdale there is a potter built 23 with twin 250 yammis on it.

Re: 20ft SeaCraft With Twin V4's??? Just Thinking OL..
 

I'll call you out on this one dunk [img]/images/graemlins/wink.gif[/img] While I agree with you that the boat must be properly designed or structurally capable of holding the motor on a bracket I disagree that it changes the running surface and puts the wave cutting portion of the boat too high in relation to the water. At rest a good bracket provides enough flotation to offset the center of gravity difference. It may take a bracketed boat a second longer to get on plane then when before it was bracketed.....but once on plane the running surface/water contact area should be virtually the same. Here are a couple pics of my boat before and after the bracket. Looks like I actually gained a little flotation. I also have some running shots that show the boat is riding pretty close to where it was when it was a notched transom. I dont have a way of loading them right now because this computer does not have the right software.

http://www.casdvm.com/photos/DSCN3275.JPG
http://www.casdvm.com/photos/DSCN4432.JPG


Strick

Re: 20ft SeaCraft With Twin V4's??? Just Thinking
 

Strick-

Was the first picture taken in Freshwater and the second in Saltwater?

Re: 20ft SeaCraft With Twin V4's??? Just Thinking
 

They are both taken in brackish water within a mile of each other. The first pic has the kicker and me for added weight and the boat does look like it's sitting really low. The kicker probably made it tilt a little to the starboard side.

I've had two bracketed boats and the only diffeence that I noticed before and after is that the boat handles like it's 2.5 feet longer. Ride is the same or better.

Strick

Re: 20ft SeaCraft With Twin V4's??? Just Thinking
 

Heres a couple pics of my first test drive with the bracket and a short clip of Capt Chuck's boat getting it on. Compare the running surfaces of the bracked boat vs the non bracketed boat. Both boats are at cruising speed 30 plus MPH.

http://www.casdvm.com/photos/gettin%20it%20on.mpg

http://www.casdvm.com/photos/DSCN4427.JPG
http://www.casdvm.com/photos/DSCN4428.JPG


Strick

Re: 20ft SeaCraft With Twin V4's??? Just Thinking
 

Dunk is right, and so is Strick. It depends upon the hull, and especially on the amount of rocker in the hull. In a previous life, I spent some time as a test pilot (strange name, that) for Wellcraft, testing engine and propeller combinations for new boats, or new factory power set-ups for renewed models.
For instance, Wellcraft chose NOT to make a 19' bracketed OB version of the Scarab hull after testing showed that that configuration porpoised continually without putting K-planes down in the water at 10+ degrees at all times - not enough hull length to rocker.
Here's a rule of thumb we came up with, which Wellcraft follows to this day. If you set the hull on the ground, balanced from side to side with the keel line at the transom touching the ground, at 45% of the vessel LOA the hull must be in contact with the ground. In other words, there must be no appreciable hull rocker in the aft 45% of the boat in order to put a bracket on the hull.
The last Wellcraft production hull to violate this rule was the 1990 26' Scarab OB center console. Rigged with a B-bracket for twins, it came factory equipped with either twin Yam 130's, or twin Merc 115's. On plane, the boat porpoised, always. Testing w/ V6 OB engines showed the aft CG made it worse. When we tested the same hull with transom mounted engines, the problem was greatly reduced. The hull had a 37% rocker point.
I have seen many 20 SeaCrafts with bracketed OB's, and all seem to run fine. A 20' Seacraft has a rocker point GREATER than 60%. So does a 23".
On the other hand, my 20' Seafari seems to like it's transom mounted V6 Merc [img]/images/graemlins/cool.gif[/img]

Re: 20ft SeaCraft With Twin V4's??? Just Thinking
 

Wow! That's experience! What a great site!

Re: 20ft SeaCraft With Twin V4's??? Just Thinking
 

Thanks for the info Frank. It's nice to have a scientific approach to things. I wonder if anyone has ever done a study and published a paper on the subject of adding a brackets.

Strick

strick

Re: 20ft SeaCraft With Twin V4's??? Just Thinking
 

I would have to disagree with several statements here http://www.click-smilies.de/sammlung...smiley-004.gif
A 30" setback of the engine does not change the center of gravity 30 inches http://floridasportsman.com/art/scold.gif The amount of buoyancy in the bracket coupled with the weight of the engine / engines also have to balance, thus the "wave cutting part of the deep vee" hull will not be changed. As a matter of fact, the 410 lbs of floatation in the Potter Bracket Eliminates the typical "Stern-Squat" and decreases the running and the at-rest draft by 3" or 4" [img]/images/graemlins/shocked.gif[/img] The boat will be drier ("NO"Spray rails),Decreased Fuel Consumption and increased Top End and Crusing Speeds with the same HP will be realized. No water into the cockpit when backing down, reduced engine noise and reduction of prop ventilation during tight turns will also be noticed [img]/images/graemlins/smile.gif[/img]

On a 20 footer, the bracket will reduce sliding of the hull. You might experience a slight tendency to porpise at a higher speed but trim tabs will correct that problem real fast. The chance of chine walking with a higher HP motor would be reduced. Added weight by a larger fuel tank and/or moving the twin batteries up forward also must be considered.

All these benefits along with the added cockpit space sold me on bracketing my SeaCraft. You can follow along with my transom transformation on another thread. OK I'm off my http://floridasportsman.com/art/soap.gif

Re: 20ft SeaCraft With Twin V4's??? Just Thinking
 

Guys, this is a very interesting post! As Frank says, I agree that Dunk and Strick are right on!
But, I am hoping I can change Dunks "47 years on the water" opinion on "My next rule is nothing under 23ft get's a bracket" on the 20' Seacraft based on my needs and these facts;
- Franks Wellcraft test pilot info "In other words, there must be no appreciable hull rocker in the aft 45% of the boat in order to put a bracket on the hull." "A 20' Seacraft has a rocker point GREATER than 60%"
- Use a Seamark Bracket, from Hermco.net "Conceived and designed by "Bill Potter" a renowned boat builder and former company owner of Seacraft offshore fishing boats (1968 - 1980) the Seamark Bracket is simply the best way to get your boat up to speed, safety and usability!"
- Full transom, love the look of a full transom inside and out. Not for "Notched Transom" fear. I feel that is over rated as Dunk states above.
- 20' Seacraft cuddy fits my fishing/boating needs and budget for a long time!
So Dunk, can we change your mind based on this. This is what all cuddy's guys are talking about; http://www.hermco.net/images/picture4.jpg
I can only take an educated guess that Strick is going to duplicate one! [img]/images/graemlins/grin.gif[/img]
Thanks Nick!!

Re: 20ft SeaCraft With Twin V4's??? Just Thinking
 

wow what a learning experience. I say no bracket on a 20. Back to the original question abot twins on a 20'. Last year, give or take a year, there was a 1984 20' w/ twin 115 hp mercs in the trader. Seemed to use the standard cut out? If you do it post some pics. [img]/images/graemlins/smile.gif[/img]

Re: 20ft SeaCraft With Twin V4's??? Just Thinking
 

Red20, thats seems like a lot of weight for a 20 on a stock transom. Df115's are 385 lbs. and the newer 2 strokes are not that much lighter. I could see possibly doing it with older/lighter 2 strokes, if thats your thing. But in my opinion if you sit 700+lbs. on a stock 20, your gonna sink.

Back to the 45% hull thing. I agree with Fr Frank on that. I have a 15 whaler dauntless, and that boat can't help but porpoise. Though my feeling would be, if you put say a hermco bracket on, which is more or less an extention of the hull it would give greater than 45% there for eliminating the problem. But I'm not going to try it.

Re: 20ft SeaCraft With Twin V4's??? Just Thinking
 

Dunk I wouldn't put twins on a 20, my 23 ran so much better with the old V8 Rude than the twin 150's it wasn't even the same boat. My theory is with the VDH the hull will pivot on the the center deadrise and get up, with the twins your trimmming it on the outer deadrise, it really wasn't the same boat and since I had an extra hole I had them stick a 55MPH speedo in, not enough, would go all the way around to the 0 peg. 1978 23 Sceptre V8 Rude, 60 should easy with a big single.