Boat Builder Central - Builder Forums

Having constructed the OD 16 some years back, I'm looking for another project. Specifically, a boat w/ a LOA of 19 to 20 feet that has the XF 20's shallow water performance but can handle the chop like the OD 18. Questions, can the rake and sides be increased on the XF 20? Or, can the OD 18 have its LOA increased and incorporate the XF's tunnel? The boat will be utilized on the Texas Coast from Galveston Bay to South Padre Island. Thoughts & Comments? Thanks....

It seems there has been the statement that the plans can be scaled 10% without major issues.
It would cause issues with the piece layouts on the plywood though.

I am currently working on an OD18 with lowered freeboard and raised decks for fishing the Texas coast. My GF18 is great for floating shallow, but is rough and wet going across the bay.

I have often thought a 20' or 21' OD with a tunnel option would be a big seller in this area. Everybody seems to gravitate to 21 foot boats, now even the 23s are gaining popularity for bay and flats fishing.

An OD18 with a tunnel will not work, sorry. There is not sufficient lifting area in the stern.
Plus the OD18 has a lot of windage to fish the flats.
To raise the sides of the XF20 is possible but that boat will never handle a chop well, that's the price to pay for shallow draft.

How about the PH22? That one seems to fit the bill. It's large, takes a chop well, still very shallow.
It cost more and require more HP.
Or the PH18?

I to have been thinking along the lines of what Clinkster is thinking about. Most of the bay boat builders in Texas are now building boats that are called "Cats". For the most part they are not true cats but more like a monohull with a tunnel of varying sizes. They sacrifice static draft for a smooth ride in choppy conditions. Claims made about how shallow these boats run vary from 1' to less than 6". If you look at pics of these boats on the trailer, then sitting in the water it would be easy to buy a 10" draft and the ability to run up on plane in a foot and a half. The TX18 design kinda fits the bill but I don't think it will run this shallow because it doesn't have a tunnel. I wonder if a guy couldn't build a XF20 with a full length tunnel and the flared front to trap air like the Flats Cat. The boat could have a sole flush with the gunwale or perhaps down a little. I realize that there are structural issues and calculations that would have to be made, not to mention an aerodynamic and hydrodynamic eval to determine the correct shapes. Using Jaques method and simply copying an existing design would yield better performance than a mold built boat due to the weight savings. Many boats built like this in Texas are being run at speeds in excess of 80mph. I have no interest in going that fast but an efficient boat say upper 40s with 100 to 150 hp could be interesting.

Randy wrote: have often thought a 20' or 21' OD with a tunnel option would be a big seller in this area. Everybody seems to gravitate to 21 foot boats, now even the 23s are gaining popularity for bay and flats fishing.

Tom,

Calm down Why do think everyone is out to get you?

What Seth meant is this: True flats boats are build for one reason....To run in shallow water. So there's no compromise, because to take them offshore is just poor seamanship.
True offshore boats are built for the entire opposite reason.....To run in deep water safely. No compromise, because to try to run them in 6" of water is just as poor seamanship.

He is saying that boats like the PH22, OB17/19 and probably even C19/21 are a compromise in that they do both shallow water and deep sea pretty well, but they don't do them as well as true flats boats or true deep sea fishing boats.

Clinkster asked a great question, and one that deserves to be answered appropriately. So check your attitude, and try to keep it somewhat sane around here.

Will

wegcagle wrote: True flats boats are build for one reason....To run in shallow water. So there's no compromise, because to take them offshore is just poor seamanship.
True offshore boats are built for the entire opposite reason.....To run in deep water safely. No compromise, because to try to run them in 6" of water is just as poor seamanship.

Will

thats right, all boats are a compromises.

A flats boat compromises almost everything in favor of low draft, but in terms of low draft, it is not compromising. A bay boat is "compromise" in that is compromises in favor of no particular use, so its really good at nothing, but OK at a lot. I guess its all in how you define compromise.

The trick in yacht design is to make the very most of the necessary compromises. A few years ago Jacques put out the TX18 as an answer. I think you should look at the PH22, and possibly the TX18. Both have relatively low draft, a lot of capacity, and can take chop

Joel, I agree with what you say about using the existing designs because they are no doubt good.. As a business guy I think you guys are missing the boat (sorry) by not having a tunnel boat in the 20 to 23 foot category. I think a little market research in Texas would show you that it is costing you money and will continue to cost you money until you have one. Down there they are the rage.
With regard to using existing designs, we have. I have a GF18 and brother Dave is getting real close on his TX18. We will soon know a lot about how both of these designs perform. We will try to collect and share info in an organized fashion so that future builders will know what they will do. I like my GF and I may really like the TX18. If the TX18 will go almost as shallow as the GF18 I may build one of those the next time. Having said that neither is 20' plus and that's what A bunch of guys in Texas want, they're buying them right now at over 40grand a copy. I think it's safe to say there is something substantive to their basic design.
Paul

Hey Paul I would be interested in the boats that are being used down there. Are they production boats or home builds like ours.?

Flats boats can be very specialized as noted above and full of compromises.

This Cat boat is built by Tran Boats in Palacios Texas. It is a popular design that is available in 18 and 21 foot versions. On these hulls they run the planer fin on the lower unit level with the water which can make the total draft, hull plus motor, less than a flat bottom. They have a smooth ride in chop and have good shallow water performance. I wonder how good a boat like this would be if it was built using our method. It would be probably 30% lighter and would require less horsepower to acheive the performance these guys get with larger motors. Note!! It looks like a TX18 from the front, it differs in that the tunnel is carried through the transom.

Neat Paul good looking boat. Basically almost a catamaran then. Let me check them out vs what we have in the Bateau catalog. Paul looking at them I'm seeing a draft of 6" when at rest. When at full power they can run in inches of water. Something similar to Davids TX18 or worse. They are definately nice boats.

Those are extremely common on the Texas Coast. A design like that with 2 sheer options would sell very well IMO. Low sheer for flats fishing, and moderate sheer for large lake, near shore activities. I'd build one.

Maybe Jacques could design a version that isn't quite so f-ugly as that.

How's it go? Ugly boats: not worth building.

Maybe it's just a bad angle?

I would design it if it was more efficient than the boats we have now but those boats have more draft and run a lower prop than our XF20.
See the XF20 study plans, I explain why a Texas scooter style boat must have a deeper draft:
http://www.bateau.com/studyplans/XF20_study.htm
It's in the middle of the page.
It is simple physics, there is no way around it. Whatever people say, you can't go around the math.
The TX18 was designed for exactly that program. It floats in less water than any cat/tunnel type boat and it runs smoother.
Several builders asked for a Texas style tunnel boat and the best way to handle the program is the TX18.

The prop depth is the same when you compare the TX18 to a tunnel boat.

I did contract work for a company that produced such a boat: tunnel cat for flats fishing. The owner did spend a lot of $ testing all kind of tunnel configurations and none worked well.
We tried every possible shape of tunnel but with a single engine, the water in the tunnel was always turbulent and we had to run the prop lower than on a monohull.
He went bankrupt but the molds are still around. About once every two years, a new company buys the molds and advertise the boat as a miracle shallow draft hull. They sell a couple, go under and another guy buys the molds, advertise etc.

If you want less running draft, go the XF20 route. Lift the water with a well designed pocket drive.

Or then, keep it simple and build a PH18.

Plus it looks like a pontoon barge with a couple of alien pods strapped on the bottom.

Vs. TX18 and FX20, which are handsome boats.

I think the question is a simple one.

Like the XF20 is basically an enlarged GF18, Can we get a design that is an enlarged OD18, 21 feet long, 8'2" to 8'6" beam and maybe a tunnel option. Like the XF20, a low freeboard and still have lower HP requirements than production boats.

Examples:
http://www.flatlanderboats.com/Flat24.htm

Regarding the statement that there is not enough lifting area in the stern of the OD 18 for a tunnel, what if the hull is 20 or 21 feet? I think Randy captured it pretty well with his inquiry and the Flatlander is a perfect example of what is needed. As information, along the Texas Coast, a lot of the fishing is done while wading. So, yes we need to run across long stretches of open water, that can be rough, and when we get to the fishing area, which is generally shallow, we jump out of the boat. We are not always polling and throwing flies out of the boat like the Florida fishermen. It's just a different way of doing it down here. Any more thoughts on a modification?

Randy, I've been looking at the various tunnel designs and a lot of the boats built on the Texas coast. Before high horsepower outboards were available there were and still are a lot of tunnel boats built for racing not for fishing. I think the function of the tunnel was to generate lift and reduce wetted surface, video of these boats blowing over is all over youtube. I think we can agree that doing that in a fishing boat would be hard on the occupants. I rode on a large Tran Cat about 5 years ago. It wouldn't go nearly as shallow as all the bs online would suggest and with a two hundred horse motor it would run about 35, it was smooth.
Moving forward to today I still look at the small Cat/Scooter boats and here are the numbers. Generally speaking they are from 18 to 15 feet long. The 18's use from 90 to 115 hp to run 30 to 35, if you look at pics of these boats the static draft is 8 to 12 inches. On the shorter boats in the 15' class, they are powered with motors from 50 to 90hp. Jaques says these boats are ineffective because the passage of the twin hulls disturbs the water in the middle therefore the motors have to be run down or deeper than even a flat bottom. Here are some interesting numbers that I have gathered over the last several months. The 15' cats with a 90 will run in the mid to high 30's and with a 50 will run in the high 20's. The 18's will run the lower speed range with a 90 and the high 30's and low 40's with a 115. A GF18 with a 50 will run 30. The GF18 is shallower and faster with the same horsepower. So it looks like the flat bottom is better in every way except ride quality than these scooter boats. We will soon know if the TX18 is a better compromise.

Randy, I know you're talking about boats over 20' so these shorter boats aren't the same. For comparison purposes I think you can reasonably extend the numbers to a larger boat except for one thing. Generally speaking boats gain significant weight for every foot of length over 20 ft.

Clinkster,

I had similar set of needs at one point. We hunted and fished the mouth of the Mississippi when I was in college. The perfect hull needed to survive hellacious wakes and nasty chop, yet still get you out of the marsh when the tide went out. I wanted to build a low sheer (i.e 15-17" cockpit depth) OD18. You could even go with a flush deck/flat sheer to reduce windage, but that would allow some water to come over the bow when you hit a big wake, so I wouldn't do it for my purposes. Such a rig would float shallow, yet get you home when the wind kicks up inshore. It is also a stupid simple mod of an existing plan. You could extend it 10% to get a 19.8' boat. You'd sacrifice a lot of offshore seaworthiness by lowering the sheer, but you'd be able to take 4' wind chop and the occasional 8' crew boat wake (I'd definitely make it self-baling). Add a jackplate, tabs and a cupped prop and you could run pretty shallow, although you'd have to slow down in the rough stuff to avoid blowing out. I haven't built it yet, but it is still high on the list of possibilities.

The PH18+10% or even the PH22 sound like they would work well also. probably better. I just happen to like dories myself.

Many hulls are drawn up by good `ol boys in their shops based on what they think sounds cool or what they already know. Hydrodynamics may or may not be considered. I can say this because I am a redneck who is currently building such a hull. The public will pay extra for a tunnel, so some hulls end up with tunnels when they shouldn't. If someone who knows hydrodynamics is honest and says he won't make it because it is a bad design, it is best to listen.

Boat fads come and go. If you hang a 250 HP motor on the end and add some sparkly gel coat, Texans will buy most of them...


Nate

Many hulls are drawn up by good `ol boys in their shops based on what they think sounds cool or what they already know. Hydrodynamics may or may not be considered. I can say this because I am a redneck who is currently building such a hull. The public will pay extra for a tunnel, so some hulls end up with tunnels when they shouldn't. If someone who knows hydrodynamics is honest and says he won't make it because it is a bad design, it is best to listen.

Boat fads come and go. If you hang a 250 HP motor on the end and add some sparkly gel coat, Texans will buy most of them...

You are a smart man Nate

I know it looks like I have flipped on this topic. Fact is I have. I was explaining to Larry the other night that I try to keep my finger on the pulse of the fishing scene in Texas. To do this I watch a couple of websites down there and since fishing is the reason boats are often discussed. The trouble with reading endless BS is you often loose track of the facts and prior knowledge you had and forgot or ditched in favor of some new-fangled BS. That happened to me. I had already asked many of these same questions, read some of the same facts and been made aware of the struggles the tunnel boat builder Jaques tried to help. I forgot this info. Nate is right on the nut, shiny gelcoat and a 250hp motor will often sell a boat. When fishermen sit around knocking back sundowners, oftentimes the good boat is the fast one or the one with the biggest motor. The crazy part is good fuel mileage is often thrown in there with these other less than true facts. When these same guys repeat this stuff for ever it often takes on a halo of truthfulness it doesn't deserve. My apologies. Paul

Paul,'
Some how you misunderstood my post.
I am not asking for a dual hull, cat, or race boat.
I was suggesting that an OD type boat, Flat bottom, with a pointed bow and angled chine, in the 21 to 23 foot range would be a great boat for the type of fishing done on the Texas coast.
The tunnel option I was referring to was a tunnel similar to what is on the XF20. Some people think you just have to have a tunnel on a bay boat, not me.

The issue is that an 18 foot boat is limited on room, and a lot of people like to fish with 4 or five people in the boat.
I think that is why the 21' and 23' boats are so popular down here.

A boat that size that would run with much lower HP than the production boats would be interesting to a number of people.

Randy, you're right what I was talking about is a general question that Clinkster brought up and something I had been wondering about. There are actually two general questions in this thread, kinda confusing.

It seems to me that a Phantom 22 is kinda what you're looking for. I think Joel built one.

Nate,

You pegged exactly what I'm looking for. At times here, you need a craft that can take the extreme chop or rough water but still have the ability to run shallow. Anyone tried crossing Aransas Bay in the winter trying to get to the flats? There is a large market for boats that have these abilities and few manufactures here in TX are: El Pescador, Shoalwater, Haynie, JH Performance, Southshore, Marshall.........Google it.

A flat bottom 21' to 23' boat, similar to the OD18. Its certainly possible, but a PH22 could be built with the same amount of effort and it will feel a lot better in a chop, draft would be about the same too (unless you build a very wide and flat boat like the XF20)

Nate,

Take a look at this.

http://harrisonboatworks.com/skiffs.html

Clinkster

I was also thinking in terms of HP requirements hence a flatbottom boat.

Also a 21 or 23 foot dory would have better offshore capabilities than the PH22, right, wrong?

Randy,

I like flat bottoms also the same reasons. A dory is a very versatile hull. It can take nasty seas and it can float very shallow. I believe you are correct that it is the closest thing to a flats boat that can play offshore. If built as designed, I believe it would have more offshore capability than the PH22. However, once you make it so that it fishes comfortable in <1' of water, I think you will severely limit true offshore capability due to sheer reduction alone. You could run out to the jetties on nice days, but you have no business running out to the rigs in such a boat. That high sheer is a necessary for the big water capability, but it will let the wind beat you up every time you turn off the big engine inshore. If you only anchor and drown live bait, you could retain the sheer, but then it is no longer a flats boat.

An "OD22" with a garbage can of builder options would be cool to see. They could make an "OD22" that could handle a tunnel, but this would be a redesign, not a quick side project. In the end, a low sheer "OD22" ends up being equivalent to a PH22. As such, they have to make sure they'd get their money back. When they already offer a hull that does the job very well, it becomes really unlikely.

I have a question. Can the PH22 be made with a tunnel with a reasonable performance expectation?

Nate