Majorgator's XF20 - SPLASHED :)

[majorgator]

And if I remember right, the only structural damage done to the XF20 was to the gunwales

seth

[chopperman]

Ouch That's still painful to look at

[majorgator]

Interesting to report that, while on the water yesterday, the XF20 had yet again a different draft. However, I'm now believing this is a matter of weight distribution rather than overall weight or buoyancy. Yesterday, it was drafting a true 3" - 4" at rest. This was with a tank of fuel (bow), fish box half full of ice (bow), 54-quart cooler full of ice (mid-ship), EMPTY livewell (stern). In short, it appears that the boat drafts as expected, with the correct weight distribution.

seth

[chlli willie]

Congratulations your boat came out great,just the fact thats its done is a huge accomplishment.How is the ride? And would you do anything different with the layout ?

[hooter]

Any updates on the performance nummbers?

I am interested in this as my next build but am a little suprised at 25 MPH with a 70 2 stroke. According to the building notes, a 25 hp will push this boat 25 mph and 30 HP will push this boat 30 mph. I realizre this is not a linear relationship and would not expect 70 hp but I am curious if a tweaking of the setup or maintenance on the motor has boosted your top end.

Not trying to medle but I am trying to get performance numbers before I saw the wood.

thx. hOOt

[Cracker Larry]

I am interested in this as my next build but am a little suprised at 25 MPH with a 70 2 stroke.

That sounds about right with a load in the boat. Actually, I think Seth has an 80 hp 2 stroke, but it's a huge 20' boat. Have you seen one?

My OD18 loaded light (relatively speaking, with a T-top and all her normal stuff) will hit about 33, trimmed up with a tailwind, with the 70 Yamaha 2 stroke. The XF20 is a much larger boat, much wider, a couple of feet longer, a lot more bottom surface and deck area. Heavier. You could land a helicopter on the front deck and play half court basketball on the back deck of the XF20 It's a BIG flats boats.

This is my OD18 tied up beside Richard's XF 20, before Red Alert was red...we both have the same 70 Yamaha, but you can see the difference in boat size.

[hooter]

I'm going to admittedly cross post. Sorry but I need answers


No I have not seen one of these.



After the Texas meet I am revisiting this performance idea and am perplexed...

If you look at a Majek Redfish line 20(which anybody who visited the Texas meet will recoginze it as there is one around every corner in Port O'Conner) the dimentions are almost identical to the XF20. 20 feet by 8 foot beam roughly. Tunnel.

The draft is a function of displacement which is determined by shape, weight, balance and volume. Everybody I've read seems to caution about putting too big a motor on the XF20 as it is "way too heavy". How is it that production manufacturers routinly put 150 HP motors on these boats (which weigh much more due the their noncomposite nature) and get speeds of 38-45 mph (and still run super skinny) but the fastest XF 20 I have seen is pushing 28 mph. I'm not a speed freak but am thinking put a little bigger motor and balance weight forward and go faster. why is this wrong?

I guess I am intrigued by DavidTX and his upgrade from a 60-90hp 4 stroke on the sled (and the resultant perma-smile). If you have a boat that is 8 feet wide and 20 feet long, what's another hundred pounds? 1/4" if properly balanced? why is this "way too heavy"? prove me wrong! Would the addition of sponsons adjacent to the motor help balance this increased motor weight by providing greater surface area and therefor bouyance (but thereby increasing weight and decrasing draft in the stern? )

I'm not a nautical engineer but I want everything in a build. Enough HP to "get it" but the skinniest draft possible. Just trying to figure out how the production boats do this but we can't seem to get the speeds they are generating.



all input appreciated.

hOOter

[D2Maine]

nm

[Cracker Larry]

but the fastest XF 20 I have seen is pushing 28 mph. I'm not a speed freak but am thinking put a little bigger motor and balance weight forward and go faster. why is this wrong?

No I have not seen one of these.

So that probably means you haven't rode in one either That big flat hull with that big square bow, in any kind of chop, I mean any chop higher than 6" if you are running directly into it, will rattle the fillings out of your teeth at 28 mph :help. You can't do it. Unless the water is flat smooth that boat won't be comfortable for the passengers at anything over20-25. It is not a speed boat, it is a skinny boat. You can't have both unless the water is very calm. And the lighter the engine, the shallower the boat will float.

I guess I am intrigued by DavidTX and his upgrade from a 60-90hp 4 stroke on the sled (and the resultant perma-smile). If you have a boat that is 8 feet wide and 20 feet long, what's another hundred pounds? 1/4" if properly balanced? why is this "way too heavy"? prove me wrong!

David's sled is a twin V, it isn't a powered floating dock like the XF20. The hull design of the TX18 is made for decent speed in a good chop, and still run fairly shallow. The XF20 is made to run very shallow, that is it's program, and it sacrifices all other qualities except load capacity to achieve it.

You can make most boats go faster with more HP, but each design reaches a point where the captain and crew, or the hull design, can't stand it no more.

[gstanfield]

The Majek Redfish 21 has an 8" draft, which is about twice the draft of an XF20. It's also a tunnel hull, not a big flat bottom so it sacrifices draft for comfort in a chop

There was a guy on here a while back that put a big 4cyl OMC on an XF20. I think it was a 140hp (or something like that) and the results were scary speed for a flat hull that slides instead of turns

It's all about compromise. Do you want 4" of draft and 30mph or 8" of draft and 45mph?