Fast Launch 26

[Pericles]

Jacques Mertens has released his latest creation.

The full plans are a very reasonable $295, but the study plans are free and may be viewed at http://www.bateau.com/studyplans/FL26_study.htm?prod=FL26

The forum is full of praise for this design and sets of plans are already in the hands of enthusiastic boat builders, who are already adding embellishments.:D :D :D :D

http://forums.bateau2.com/viewtopic.php?t=15658

Pericles

[Tad]

An "offshore capable" flat bottomed boat?

No thanks.

Tad

[eponodyne]

Stretch it eight or ten feet, get the cruising speed in 4-foot seas to 22 kt (WFO in a flat calm to maybe 32 kt?), and maybe some vee in the bottom, and I'll start to be more interested. Pretty boat to be sure; but a pretty narrow set of operating parameters. I am, however, very impressed with Mr Mertens' creations, even if they're not entirely to my taste. He sure seems to do a workmanlike, thorough job with what he's selling.

[Pericles]

eponodyne,

The FL26 is designed specifically in response to requests from his forum members. Jacques knows his marketplace. I'd love to build an electric version for use on the River Thames.

http://forums.bateau2.com/viewtopic.php?t=14669&highlight=battery+powered+fl26

I think you will be impressed with his TW34 when it's ready.

http://forums.bateau2.com/viewtopic.php?t=11743&highlight=tw34

http://forums.bateau2.com/viewtopic.php?t=11346&highlight=tw34

Tad,

The CX25 might have more appeal to you, but your Stahl 29 already is an excellent design.:D :D

http://www.bateau.com/studyplans/CX25_study.htm?prod=CX25

Best regards,

Pericles

[PAR]

I've had some success with relatively deep forefoot, flat bottom designs, but I don't think he'll get as comfortable a ride as he's hoping from this new design, particularly in broken water. Managed properly a well designed flat bottom boat can take open water, but few know how to handle a boat, flat bottom or not, in confused seas, so they're reputation grows out of the skipper's inabilities to drive in a seaway.

[Pericles]

PAR,

What time do you get up in the morning? You last post is timed at 4-25 AM in Florida.:D BTW do you have a website?

Regards

Pericles

[tom28571]

I've had some success with relatively deep forefoot, flat bottom designs, but I don't think he'll get as comfortable a ride as he's hoping from this new design, particularly in broken water. Managed properly a well designed flat bottom boat can take open water, but few know how to handle a boat, flat bottom or not, in confused seas, so they're reputation grows out of the skipper's inabilities to drive in a seaway.

I know some who have success in open water in flat bottoms by trimming the stern up and the bow down. Still, I prefer a V because the same technique works even better there. There is loss of top speed because of a non-optimum trim angle giving greater skin resistance. It's a price I gladly pay on my boats.

[Pericles]

Tom,

This is where the FL26 will score.

http://www.electric-boat-association.org.uk/members.htm

http://www.electric-boat-association.org.uk/charging.htm

http://forums.bateau2.com/viewtopic.php?t=14669&postdays=0&postorder=asc&highlight=battery+fl26&start=0

Jolly boating weather.

http://www.etoncollege.com/eton.asp?di=1359


We are mad you know!!:P :P :P

Pericles

[u4ea32]

Still seems like adding a V -- say 15 degree deadrise -- would transform the FL26 with just a few hours more labor.

Neat boat other than the flat bottom.

[Pericles]

David,

Choose another boat if you want a Vee bottom. The FL26 calculations are for the boat as it is. Jacques puts his good name and reputation behind his boats and unauthorised modifications change the legal position between designer and customer. The LB26 is the boat for you if everything else of the FL26 matches your needs. Compare the two.

http://www.bateau.com/studyplans/LB26_study.htm?prod=LB26

http://www.bateau.com/studyplans/FL26_study.htm?prod=FL26

The Panga 28 and Abaco 23 are also coming along.

http://www.bateau.com/

Regards,

Pericles

[charmc]

Pericles,

You make a very good point. The FL26 is designed along traditional lines, as an economical and easily driven hull, giving a reasonable cruising speed with less than half the power required to drive a hull whose V is carried to the transom. All designs are a compromise, this one appears to favor running economy while not completely sacrificing seakeeping ability. It is what it is, and changing the bottom would make it a different boat.

For many years Pacemaker and Egg Harbor built rugged sport fishing boats designed to navigate the rough inlets of the New Jersey shore and the offshore fishing grounds of the North Atlantic. First in wood, then in fiberglass, the basic design used a deep, narrow entry which transitioned to a flat bottom aft. Even the latest fiberglass designs had only a few degrees of deadrise at the transom. These boats earned a reputation for being able to handle rough seas. I owned 3 over the years, including one of 26', and will testify personally to their excellent seakeeping capabilities.

Moppie was developed to win races, and Dick Bertram began building deep V sport fishing boats for wealthy tournament fisherman who wanted to be first out and back and were willing to pay the cost. There's no question that a hull with a V bottom will go faster in rough seas, and ride well at those higher speeds. It's not that a boat like the FL26 will not ride well in rough seas compared to a V bottom design; just that the V bottom will enable higher speeds in those same seas if the owner is willing to pay the cost of more power and higher fuel consumption.

The designer did say she's offshore capable, not that she's designed to be offshore most of the time. This design clearly is intended for operating mostly in sheltered waters.

18 mph cruising speed in a 26' hull on 50 HP ... there's a market for that.

[Tad]

as an economical and easily driven hull, giving a reasonable cruising speed with less than half the power required to drive a hull whose V is carried to the transom.

Please show me a 26' LWL, 3000 pound, 8' beam boat that requires over 100HP to manage 15.6 knots?

The most important factors in any boat's performance and efficiency are length and weight; I say this over and over on this forum. Next most important factor is the engine/gearbox/propeller. Section shape is a minor factor. I would suggest that three hulls (flat, round, and vee bottom) of identical dimensions, weight, and power will run within a few mph of each other in dead flat water. Each form might have an edge at some particular speed.

In 1958 Tom Gillmer ran a series of tank tests on light displacement fishing launches. He worked with four hull forms of between 29' and 34' LWL. One hull was a standard round-bottomed Maine lobster boat, next was deep vee lobsterboat (Bolger design) then a Chesapeake crabbing launch of very low deadrise (very similar to the subject of this thread). The final model was a Hooper Island boat of high deadrise forward with flat bottom aft. The round-bottomed Maine hull was the best, the hooper Island boat the worst, differences were on the order of .5-2 EHP at various speeds.

These tests are published in Fishing Boats of The World, Volume 2.

[charmc]

Scanning through a large number of tests, I found that most 3000 lb production boats had moderate to deep v hulls and hit that speed at between 2500 - 3000 rpm. HP ratings ranged from 150 - 225. Checking mfr's power curves, I found that 2500 rpm typically yields about 50% of peak power. That translates to at least 75 - 110 HP.

No, this isn't the precision needed for an exact comparison, but it seems to indicate that the FL26, at 50 HP for similar performance, represents a significant advantage in operating costs.

[charmc]

Tad,

I took a look at your site and your Downeast 26 with a moderate V (15 deg deadrise). Interpolating from your published figures, I would estimate 60-70 HP at that speed. 20% heavier (3600 lbs), 20-40% more power, if I'm reasonably accurate.

So the FL26 has some, but not nearly as much, of an efficiency advantage compared to your design. Maybe the answer is that most production boats are optimized for higher speeds, or just for easy production (constant deadrise).

Overall, with the higher freeboard and bow flare, I would prefer to be in a Downeast 26 if I were spending much time offshore. And she's good looking, also.

[Tad]

Charlie, I wonder about the length (LWL) and beam of the 3000 pound boats you are using to compare. Realize that published figures are often wildly inaccurate, especially weight. What I've found is that there are few if any comparables. The Van de Stat Admirals Launch might be close but there's little performance info available. Some of the old Atkin designs are also close, but performance data is vague and questionable.

So if we start from the basics of length, weight, and speed I find we have a speed length ratio of 3.05 and displacement/length of 76. A series of resistance curves I have indicate something between 60 and 80 pounds of displacement per hp will achieve the required 18mph. That puts power between 37 and 47BHP.

Using Hatch's method I find a round bottom most efficient at this weight and speed, the round form requires 31.4BHP while the vee requires 35.7 for 18mph.

Crouch's formula requires 30HP on the nose. And Keith's 39.3BHP.

As always your mileage may vary!

Tad

[EStaggs]

Tad, run your numbers against the S&S commuters and Reuel Parker's commuters as well. Jacques penned his design with an eye to those boats, as well as Bolger's Blackbird design. Lightweight commuters capable of crossings. The other boats, however, are all warped plane boats with a slightly higher speed potential.

I think another feature of his boat isn't necessarily outright efficiency. Its a development of efficiency v. construction ease. When you see that the V form and the flat bottom form are within 1-2 bhp, and construction time can be significantly reduced (bear in mind his customers are not shops or pros, but backyarders like myself) with very similar performance characteristics, it makes some sense.

I find myself drawn to your Alder design, which is extremely similar hull-wise to the FL26, in a dimunitive size.

For the readers:

Alder:

http://www.tadroberts.ca/services/small-boats/images/Alder-colour.jpg

FL26:

http://www.bateau.com/images/boatpics/FL26_wire_bow.jpg

In combining his construction method (developable panel cored composite) with the specified cruising grounds (Florida/Carribean/Gulf), I think the design stands well. His method would not allow for round bilges or a round hullform such as your methods will.

With that in mind, do you still find the hull a poor adaptation as compared to a V, which with his method would have to be developed? Bearing in mind there is no strip hybridization in his repertoire, the V sections become either very deep or rather inconsequential when built in 3/8" okoume core.

E

[Tad]

E,

There really is no way that I have to compare this mythical (until built) boat with any real boat. Especially as I have no direct information on the boats you mention. Published numbers are highly suspect; I don't believe anyone's weights unless I measure floatation and have the hull model to check for myself. I have no way of knowing what this boat will actually weigh when its built, thus the "real numbers" are elusive.

I agree the flat bottom can seem to simplify construction but I think it's a chimera. Compared to a vee bottom you have eliminated one (stitch & tape) full length seam (centerline) and two edges that must be trimmed to shape. That's all! You still have to make chine logs (or not), and the rest of the boat is the same. As Phil Bolger says, amateur builders will build boats that appear simple to build.

I firmly believe a flat-bottomed boat will be less useful and less valuable long term. If you are going to build a boat, build the best boat you can with the materials and time at hand. Around here we have a wind against tide chop of about 2' height that would be murder to buck in a flat bottomed boat, never mind going offshore. I know a vee bottom of these proportions and weight could be a real sweet ride in such a chop.

[EStaggs]

Interesting view Tad.

The next boat I referenced was Reuel Parker's commuter:

http://www.parker-marine.com/commuterbig.jpg

Here is a quote about the boat built:

The entire construction process took eleven weeks for the prototype. Materials costs, including engine, tankage and awning, were about $25,000. For power we settled on the Honda 90 four-stroke. Steering is hydraulic, with a 24” stainless steel destroyer wheel. Single-lever control is Morse. “Magic” cruises at 19 miles per hour consuming slightly over 4 gallons per hour, and runs wide open at about 24 miles per hour.
Because of her extreme shoal draft and light weight, this design is not intended for use in rough water, for long off-shore passages, or for being driven hard for extended periods in high chop. She is, however, safe and comfortable, and capable of crossing the Gulf Stream to Cuba and the Bahamas in settled, predictable weather. And she has the fuel range to make such trips practical.

I do know that the FL26 is designed to keep her forefoot in the water at all speeds to reduce pounding, but obviously until there is an existing copy, you are right about having trouble making empirical points. I just see that using plywood cored composite to create a v hull on this boat would cause it to be significantly deeper in that the conic sections of the plywood force the v to either be deep with a high deadrise angle or shallow with a low angle, thus providing very little improvement in ride, especially when the boat is designed to keep her toes wet.

E

[Tad]

E,

I don't know where the forefoot might be at 18mph, but I do have some thoughts.....given the pic above.....

Yes, a vee would be deeper. There is a very honest piece by Reuel Parker on the Commuter 36 at age 10 in WoodenBoat #199. Unfortunately it presents some information that conflicts with what you post above and nothing on actual weight at all. He states 17 knots cruising speed burning "about" 5gph with a 90 HP Honda. Top speed was "about 21 knots".

"Driving into chop 12" or larger (in winds over 10 knots), it becomes necessary to slow down to prevent hard pounding.
The Commuter 36 is not an offshore powerboat."
Apparently the owner lent the boat to friend who drove her so hard into a head sea that the #2 bulkhead (guessing aft end of vee-berth) was broken at centerline. Reuel has since designed an alternate deeper v-eed bottom with 12" of draft (4" greater than the original) and displacing 6000 pounds.

Well "about 5gph" might be 62 HP or it might be 44HP, I have no figure on specific consumption for the Honda.

[charmc]

Charlie, I wonder about the length (LWL) and beam of the 3000 pound boats you are using to compare. Realize that published figures are often wildly inaccurate, especially weight. Tad

"Scanning through a large number of tests, I found that most 3000 lb production boats had moderate to deep v hulls and hit that speed at between 2500 - 3000 rpm. HP ratings ranged from 150 - 225. Checking mfr's power curves, I found that 2500 rpm typically yields about 50% of peak power. That translates to at least 75 - 110 HP.

No, this isn't the precision needed for an exact comparison, but it seems to indicate that the FL26, at 50 HP for similar performance, represents a significant advantage in operating costs." charmc

Tad,

While you may be right that published weight figures are often inaccurate, I was comparing data from production boats, Sea Ray, Grady White, etc. The inaccuracy of weight data on such boats, in my experience, is typically on the low side, i.e. they are usually heavier than the marketing literature describes. The hulls I described tend towards the "deep vee" that marketing types promote so the buyers think it's a derivative of a racing hull.
You are describing carefully designed custom boats, and, as I stated, I agree that the efficiency advantage of the FL26 compared to other custom designs will be less than its advantage over production designs. There is still some advantage. I stand by my numbers.

Your subsequent comments to E about the versatility of a vee bottom design to the FL26's flat bottom aft are valid, as are his about simplicity of construction and the market for this design. I'll add that my years of operating power boats from 17' - 31' in the North Atlantic and numerous inlets has demonstrated to my satisfaction that shallow vee bottoms have no measurable ride improvements over flat bottoms.

Again, keep in mind that the FL26, like the Reuel Parker design discussed, is not intended to go offshore as a primary "mission", while being capable of going offshore if desired.

[Pericles]

The Landau 20 has a twin tunnel hull form for insignificant river wash and sparkling performance in coastal waters. Quite economical to run as well.

http://www.selectyachts.co.uk/landauhome.asp?ArtID=18

http://www.selectyachts.co.uk/landauhome.asp?ArtID=261

The Landau 29 video is entertaining.

http://www.selectyachts.co.uk/landauhome.asp?ArtID=254

Better late than never? :D

Pericles

[Tad]

Charlie,

Apparently I'm not stating my thoughts very clearly.

In post #11 you stated;
"The FL26 is designed along traditional lines, as an economical and easily driven hull, giving a reasonable cruising speed with less than half the power required to drive a hull whose V is carried to the transom."

In that statement I assumed that you meant a boat of similar dimensions but with a vee bottom. Apparently what you meant was a 26' Sea Ray that weighs 6000+ pounds and is 9' wide? To me it makes perfect sense that a boat weighing twice the proposed 3000 lbs of the FL26 should use twice the HP for similar speed. I don't see how that validates the FL26 hull form?

So in post #12 I stated;
"Please show me a 26' LWL, 3000 pound, 8' beam boat that requires over 100HP to manage 15.6 knots?"

So far no specific examples have been posted. Perhaps there aren't any examples of this configuration, or they are just not easily available. At any rate I apologize for my confusion.

If you are comparing the FL26 to a production boat advertised as weighing 3000 lbs, that boat will only be about 20' overall. Shorter length will require more power for similar speed. If you are comparing the FL26 to a production 26' boat, the waterline will be shorter (much shorter at pre-planing speed), the beam will be greater, and weight will be far greater. And yes, every production boat actually weighs more than advertised, and the real weight is unknown. In any of these cases the reason for higher required power is obvious, increased resistance due to shorter length and greater weight. Thus (to me) your comparison is invalid. I.e., you are comparing apples and oranges.

My postings above questioning the quoted capabilities of this design are written in hopes of avoiding a rash of inexperienced folks drowning after building flat-bottomed "offshore capable" boats. This very shallow, low sided, protected water cruiser will be in big trouble if she lost power and a wave came aboard. The cockpit is huge, and unless it is equipped with relatively huge drains, the boat is unsafe "offshore". ISO standards on cockpit drainage will require (roughly) a minimum of two 6" diameter drains for a cockpit this size. To characterize this type of boat as offshore capable is (to me) irresponsible.

Tad

[charmc]

My postings above questioning the quoted capabilities of this design are written in hopes of avoiding a rash of inexperienced folks drowning after building flat-bottomed "offshore capable" boats. This very shallow, low sided, protected water cruiser will be in big trouble if she lost power and a wave came aboard. The cockpit is huge, and unless it is equipped with relatively huge drains, the boat is unsafe "offshore". ISO standards on cockpit drainage will require (roughly) a minimum of two 6" diameter drains for a cockpit this size. To characterize this type of boat as offshore capable is (to me) irresponsible.

Tad

Tad,

I'm not a designer, and nothing I've posted should be taken as critical of your designs. If anything I said sounded like design criticism, I'm sorry, that was never my intent. I have a lot of respect for your work and for your contributions to this forum.

But no, I haven't been so foolish as to attempt to compare 6000 lb+ boats with 3000 lb vessels, or 20' boats with 26' boats. There were slight variations in waterline length, but no beams over 8' in the tests I selected (most were center console outboards, to stay within the weight range). Unfortunately, I can't cite specific side by side models here, as what I did required a few hours of research (it is damn difficult to find boats that size that don't weigh a jillion pounds), and I won't do it again. I didn't save individual tests, but I made notes and presented some typical performance figures. Yes, that means you can criticize my method and results as imprecise and therefore limited. In fact, I said that myself.

My point about the FL26 was simply that that particular design appears to have an edge in operating costs over others I've seen in that size/weight range. A very large edge over production boats, a smaller but measureable edge over custom designs. When I said 18 mph with 50 HP was economical, you said that no boat of that size/weight range should require more than 100 HP for that performance. I understood that to validate my position. I continue to stand by my numbers, and I believe your own numbers (I assume yours are not "wildly inaccurate" :) ) show a small efficiency edge to the FL26 compared to your Downeast 26.

On the subject of whether it is a good design as a boat for people planning to go offshore occasionally, I have to agree with your comments above. PAR made a good point earlier, stating that such a boat is offshore capable ... in the hands of a good operator ... the Wooden Boat 199 article about the 36' Commuter supports his point. When evaluating a boat, I tend to think in terms of my own experience. The FL26 will not be dry, comfortable, or easy to handle offshore if caught in a squall, but I don't think I'd be worried. I forget, though, that inexperienced people fall in love with a dream and build a boat.

So I find myself agreeing that characterizing the FL26 as offshore capable, without any caveats, is perhaps misleading. I don't know if I'd say irresponsible, but there should be a more detailed description of "offshore capable", maybe by adding "in the hands of an experienced skipper" or similar wording.

I would recommend the FL26 as a good looking, economical boat for folks to run in sheltered waters. For myself, I would, in fact prefer your Downeast 26, even though I'd pay a bit more to run her.

[EStaggs]

Interesting, as I lost track of this thread.

In Jacques' words, he actually is very adamant in the plans information and any inquiries about the boat about her usage. He is very quick to point out that the seaworthiness of the boat rests in the operator, not in the design or inherent abilities of the boat. I would venture that he agrees with you on seaworthiness 100%.

I would, however, like to see how your 26 compares side by side, as I was on your site the other day looking at her. I think it would be informative for those of us who are looking at maximizing efficiency while retaining a 20-28kt speed burst ability.

As always, very informative post!

E

[Pericles]

Eric.

A more "like for like" comparison would be between Jacques' DE 25 and Tad's lovely DE 26, which I have admired since the plans were published. Probably the long cockpit version DE 25 is the nearest match.

http://www.bateau.com/studyplans/DE25Cockpit_study.htm?prod=DE25Cockpit

On balance, I believe the wide chine flats that the DE 26 possesses will encourage it to plane earlier, by one knot, probably!

http://www.tadroberts.ca/services/small-boats/down-east26.php

Tom Lathrop incorporated wide flat chines into his Bluejacket boats with remarkable results.

http://www.bluejacketboats.com/designing_liz.htm

In the end, it has to be about good seamanship and making the right choices whilst at sea. :D :D

They are all great vessels, each of which is a credit to their designer!

Pericles

[EStaggs]

Im seriously considering doing a modified DE23 of Mertens design with an open aft section of cabin such as the 26 of Mr Robers, but after seeing that the 26 utilizes the SAME engine as the 23, and the same fuel burn rate, with similar performance numbers (only slightly slower), Im considering it.

Obviously its a more complex build as I dont think Tad's boat has true conic sections allowing plywood to be used for all panels (I believe it requires some cold mold/strip type work on the bow), but the extra few feet make an IMMENSE difference as far as interior layout is concerned, and a much more usable aft deck.

I am also curious if it is bracketable, as any boat this size will be used for mothershipping our sea kayaks in the San Juans/Puget Sound/Gulf Islands.

E

[Tad]

Oh boy...a bunch of posts in row here....

First....I don't want to get into a "my boat's better than yours" type of argument. It isn’t. I believe all boats, given reasonable design and construction, have their place....except for those three story white ones with the black windows....you know...

Second....I am embarrassed about the Downeast 26 name, I had no idea of the existence of Mr. Mertens DE25 or I would have done something different. Actually I have changed the name to the Berry Point 26, but that hasn’t made it onto the website yet...and it may be too late.

Third....Seaworthiness is a huge subject but we (designers) cannot say it all rests with the operator, that's a copout. Part of being a designer is sending folks out in peril of their lives, as a designer you had better take that seriously. Home builders are often neophytes at the boating business and are perhaps more apt to get into trouble. I believe one has to think about this, a sunny day on a small lake is very different than a cold night offshore. Where is trouble more likely to crop up?

Fourth....E...given the same beam and depth, the longer boat will be faster (or use less power for the same speed) even though it weighs more.

[EStaggs]

Tad, is your boat capable of using a bracket for the outboard?

Is there a place I can find more info than on your website (study plans more descriptive than the .dwf files)? Im finding this boat to be very interesting.

E

[Pericles]

Eric,

Jacques' DE 25 is the stretched version of the DE 23. I purchased plans for both the LB 26 and the DE 25 Long Cabin version as I like to hedge my bets.:P Nesting the marine ply would be the greatest difficulty in stretching the DE 25 any further and could put costs up significantly

It would also have implications in the UK with compliance to the RCD as the finished vessel would not be as the designer calculated. It can be done but, the documentation would cost more.

http://www.icomia.com/technical-info/document.asp?TI_ID=11

Tad's Berry Point 26 has more of the look of a Down East lobster boat, see page 52. NIKI.

http://www.woodenboat-digital.com/woodenboat/20070910/

The nearest Jacques gets to that look is the Novi 23.

http://www.bateau.com/studyplans/NV23_study.htm?prod=NV23

Its the three window look of the DE 25 that ticks my box, as it is with the Tolman Skiff, although the wide variety of cabins styles on a Tolman leave a builder with many choices.

http://www.fishyfish.com/tolmanskiff.html

As mentioned in an earlier post, they are all great boats. We are spoiled for choice.

Pericles

[EStaggs]

P, I have no interest in stretching the designs. I would build the 23 as it sits, or Tad's 26 as it sits. Stretching that would be a hassle, and the 25 is really quite similar in length to the 26 if that were the case. The problem being the 25 requires more power for the same speed (Id guess Tad's lifting strakes are probably the efficiency-builders here).

I have that issue (been a subscriber for years) and liked NIKI, but she wouldn't be too friendly in the strait of Georgia or Juan de Fuca on a wind-against-tide day. I need a bit more freeboard. This same freeboard issue is what keeps me from getting FL26 plans. My current project (Mertens LB22 NINA) has the same low freeboard, so it will get very limited use outside of the lake we live on.

Freeboard is uber-necessary because I like to salmon and halibut fish on occasion, both of which take place in areas that need a boat with freeboard. The outside of San Juan island takes the brunt of the Juan de Fuca waves, and the trolling route causes the boat to take the majority of waves directly to the side of the boat. Nauseating roll ensues, etc etc. Ive had a few too many spray-over-the-rail events to have a shallow boat out there.

Im rather fond of the Berry Point (hoping to learn more about it), and Id love to see the pilothouse fit out, to get an idea of accomodation. This is probably a year out (rowing shell and Tom Hill's Long Point skiff are due up first), but something that Ive been putting a ton of thought into.

E