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My needs/interest is for a simple, lightweight fly fishing boat with ample casting surface area. My application will be freshwater rivers and saltwater flats yet I want the boat to be capable of handling the ocean side of the Keys where feasible. I prefer to build a boat that can handle chop rather than a pure poling vessel so this brings me to the Phantom designs because of their shallow vee. The choice of one Phantom over the other does not matter but it is clear the material cost, build time favors the PH18 because you get more boat for similar cost and effort. My comments are based off Study Plans; I have not purchased plans yet.

Consider a typical load of 2 persons and gear. I plan a Tohatsu 40-60 hp because their weight appears to be the lowest in the industry for mid-range outboards at just over 200 pounds. I will opt for the 15" shaft if this is best for weight considerations but this version only saves ~ 4 pounds. Their 60 hp weight is listed as 237 pounds and I may need to exclude this model for weight considerations. Similarly, their factory jet option will help with skinny water usage but this adds too much weight to be useful. Small weight differences can make a difference in lighter vessels like these and Yamaha mid-range outboards appear to be heavier in their product literature. I do expect some use with 3 persons aboard but this will not be often so let's base any comments/calculations on the 2 person occupancy. In fact, here is the weight breakdown (pounds) for our family: Dad (165), wife (112), and teenage son (126). I will say teenager's can eat an enormous amount of food!

My goal is to minimize weight as well as static and dynamic draft. In this thread JM-G states the lightest PH16 prototype weighed 550 pounds. See the 9th post in this thread:
viewtopic.php?f=8&t=64790&p=464385&hilit=PH16#p464385

This is considerably lower than the 750 hull weight listed for the PH16 in the study plan. Does anyone recall what was done to achieve this weight reduction? What was the draft of this prototype?

Features I would like to add are:
A poling tower/casting platform over the outboard. I will restrict this to reside within the dimensions of the deck rather than extending it further rearward of the transom if needed. Material choice is likely to be aluminum.
A small central console - Again; likely aluminum sheet because Al fuel tanks weight less than their composite counterparts.
A front deck mounted casting platform
A tunnel - to reduce dynamic draft
Fuel tank - A portable tank mounted under the fore deck seems best given my desire to save weight but these are always plastic.
Trolling motor - I prefer to exclude this but if mounting one at the bow helps keep the outboard skeg clear of 'matter" I'll install one.
Battery/batteries - Up front but I'm uncertain where.
Chain locker - At the bow
Unsinkable - Does this mean add foam?

This thread is also good motivation: 'PH16 KISS'
viewtopic.php?f=8&t=62177&hilit=PH16

As is this one. It looks like a skeg may be mandatory and I was pleasantly surprised at the description JM-G gave regarding how spray rails should be fabricated/located.
viewtopic.php?f=8&t=64807&p=466529&hilit=PH16#p466529

Should I consider scaling either design to obtain my goals? I do not see borrowing foam core from the smaller PH15 as useful; because the fiberglass this requires is likely to result in weight gain. It is difficult for me to provide a specific value of desired draft but I would like to see if 4" is feasible. I will do the work to achieve this.

Let me know if you have questions. August is a busy month...I'll monitor this thread as best I can.

Rick

The designer believes that keeping a boat light is an advantage, and keeping it simple helps keep it light. A few builders have gotten to the end of their build with spartan, really light boats, but most builders follow a different path. I don't know how they got that Phantom hull so light, but you can be sure it didn't include anything extra- no poling tower, no glass where not required, no tunnel, etc. etc. It sounds like you are already struggling with that (which is normal and good); choosing a design and building your boat involves a series of compromises that need to be justified to your program.

I'm sure you'll get some good advice here. Good luck with your journey!

As a first time builder I found it very hard to control weight on my PH because of my inexperience and decisions. I know I used too much resin although I got better towards the end. I used more fiberglass than called for. I used 6 oz under the decking and sole to reduce the chance of water intrusion to the plywood and 12 oz inside from the deck to the top of the gunnel. I raised the sheer line 2" and raised the sole 1". I installed a 24 gallon aluminum gas tank in the front deck, I added front deck hatches instead of using the flat deck with a rear cutout, I added a 24v spot lock trolling motor which means two Group 29 batteries in the console in addition to the 12v starting battery at the back of the boat. I added strakes because I eliminated the keel and added reverse chines to knock down water spray. Without the keel my boat will slide in a turn if you don't slow and trim down. The reverse chines do a wonderful job keeping the boat (and driver) mostly dry.

To make everything go I bought a 90HP Mercury 4 stroke weighing 385#. I built with a minimal transom cutout (about 1-1/2") because I wanted to maximize the flat back deck which with the 2" additional sheer and raised cutout required a 25" lower unit and a manual jack plate to adjust the motor height. With all of the additional weight the 1" raised sole keeps the decks draining through the scuppers and dry even with two people fishing off the back deck. With a spot lock trolling motor and a wind the front of the boat will weather vane into the wind. If you are fishing a reef the reef will be behind you so both fishermen will fish off the back deck. Alternately you can spot lock to the side of the reef and cast across the wind which can be tough if the wind is ripping pretty good.

Do I regret adding what I did? No, it has proven very useful to the type of fishing I do, shallow inland salt water lakes and marshes for speckled trout and redfish, and freshwater marshes and huge freshwater lakes for bass. My loaded depth with two 200# fishermen, all their gear and 40# of ice in the 75 qt. ice chest is about 9" based on the water scum I have to wash off when I get home.

I rode on a PH18 that had a tunnel because the owner/builder wanted to fish the very shallow Texas flats. He was very dissatisfied with the performance (30 mph max with a 140 HP 2 stroke motor) and eventually filled it in and gained the performance he was looking for. He added tunnel vents to aerate the tunnel when he was moving to reduce the drag caused by the tunnel but they were insufficient. He also added extensions to the rear deck/hull, some call it a keyhole transom, to help support the motor with more flotation and reduce squat on takeoff. I believe those were beneficial.

Good luck on your build. As always please post pictures.

Thanks for your responses. I also have to be honest; primarily with myself. If these boats cannot do what I hope they can do I have to find a different way to accomplish what I need to do. The difficulty is I see no way to get around two boats and the likelihood that I can afford that is zero. I would have to redirect my attention to building a Kingfisher/Recurve from Cajune Boatworks to begin with and see where this gets me.

I do not know what was done to obtain the 200 pound weight reduction of the PH16 prototype. I am hopeful my post will bring this information out in a more public manner. In addition to this, I do not know if the 550 pound prototype will draft less than the 6" listed in the Study Plans.

Edit - Note I was not, and would not, consider attemoting to design a tunnel. For me to implement this feature it would have to come from Jacques. A simple conclusion to come to that may be relevant is he does not appear to offer this in the information presented on the webpage. It could be the hull design is not a candidate for this.

Despite the drumbeat here against, the way to make a boat lighter is foam core and vacuum. But there is a cost, both in dollars and time.

And foam core is pos buoyant, ftmp, so very little marine foam would be used. Buoyancy foam does add weight.

To satisfy your open ocean wishes, an 18' boat is about the least. I have a 16' skiff and it is just a little too small for anything bigger than 2' or rollers and 2' chop. All planing boats in this size range suffer in bigger seas. I purposely go out in the morning against the wind direction on big waters, so I have following seas coming back.

I think you are a bit uberfocused on weight. I wasn't and I paid a dear penalty using mat backed 1708 tapes in my build. I regret it some now and calculate about 150 pounds per hull or 300 pounds penalty and about 150 pounds of that is resin or about 16 gallons at $100/. But that said, if you find yourself paralyzed on weight, then you are in too deep.

Smaller fillets are a simple way to reduce weight and epoxy expense. If I could go back, all my non-appearance fillets would be 1/4" radius versus 3/8".

If I were you, I'd build the ph18 and power with the Yamaha F70.

Balance/trim is probably more important than total weight. A forward livewell is a great way to help handling if you get into a chop. You want 25 gallons. It helps tons and even when trolling. Placing the console after launch is also wise. Not ez, but wise.

Remember all weights in a boat are not masses, but moments. A boat is a seesaw, not a fat or skinny girl.

Building in foam is its own adventure. If you provide reliefs for tabbing or tapes, then you use less fairing compound and the boat WILL be lighter.

To make a stock plywood boat lighter generally means skipping sheathing the inside. This has a cost of longevity, benefit is faster build and lighter, but a soaked bilge can be trouble.

When you are undecided, the best way to deal with it is to work on the sor (statement of requirements), not to search for more boat plans.

For example, I bought a plan here, but I didn't like the helmsman's height above the water driving the boat. My sor got tweaked after spending money on the plans and then being disappointed with a beautiful design that did not fit my wishes.

I do not have a lot of skinny water experience, the engine seems to be the biggest issue and I'd think a hydraulic jack plate mandatory.

Anyhow, let the needs drive the plan. If you want an ultralight boat; you either go foam or sheath ply less.

An 18' boat with high waterplane area will be less affected by weight, so keep that in mind. I had a 14' skiff years ago and I could not sit on the bow and operate the trolling motor because the boat behaved like a bobber with an engine.

I strongly recommend an 18' boat. It is a little much for the over 75 crowd, but will suit you well. Offsetting your weight forward when casting and using the front motor with an engine that is not too small will help.

I strongly recommend an 18' boat. It is a little much for the over 75 crowd,

Huh? I can't let that go unchallenged!

I am not yet in the 'over 75 crowd", but headed that way. I have NO problem launching and retrieving my 22' x 4,000 lb boat solo! Its just a matter of having the right set up, ie drive-on drive-off trailer, a Boat Catch and a ladder on the front of the trailer!

RVC as Jacques noted in his post the 550lb PH16 was bare hull while the Study Plans includes hard ware, probably a gas tank and other accessories. So you are trying to compare apples to oranges.

Now to building in foam, Jacques has consistently said that until you get over 22', foam will weigh more than plywood do to the excess fiberglass and epoxy needed. The only advantage is that resale value will be greater. but cost will be about 3x greater.

I also agree with fallguy that if you are going offshore the PH18 is a better choice for you. With the same load you will draft shallower than the PH16 in the flats. The difference n weight between the two boats is negligible for the additional two feet, 50lbs per the study plans. Also a F60 Yamaha will push you near 40mph at 1400lbs, an F70 into the mid-40's.

Well that is all I can give you for now.

Tom

Thanks Tom - I just reviewed this thread again

viewtopic.php?f=8&t=64790&p=464385&hilit=PH16#p464385

and it is not clear to me that Jacques is referring to an empty hull but this is fine. The primary reason I cited this thread was to determine if I could realize this weight and this now seems unobtainable. can I improve upon the 800 pound spec. for the PH18? I do not know. I have to agree with your comments regarding foam/glass/epoxy layup schedules because this is what I have been told repeatedly. I do not know this from direct experience but I have built foam core composite structures. Use of vacuum and soaking/blotting up suspect excess resin is a big tool in weight reduction of composite structures but even a microskiff is a much larger project than I have fabricated before. As swglenn stated in his response first time builder's - me - make similar errors. I am trying to prepare to reduce or prevent these. Fallguy1000's suggestion for the PH18 is appreciated because I have no saltwater boating experience but I have been on two of the Great Lakes; in much larger boats. If all of this happens and I do venture to the ocean side of the Keys it will not be far from them.

The speed estimates you provided are extremely helpful. I cannot imagine going 40 mph on a boat this size, but this helps me to plan. There is a significant difference in the weight of a 60 hp and 70 hp outboard. I think this is ~100 pounds.

Rick

I think I'll provide an unsolicited 2¢ on boat length.

As the forum idiot who takes a v12 out about 3mi (sailing with rollers under 2', 5sec and wind < 10kn) and will motor out 6mi in a neighbor's 17' Sportsman (rollers under 3', 3sec) and will run a buddy's 22' Trophy out 15mi+ (seas at 5', 3sec and wind stupidly in the mid 20s) and crew on a J30 about 100mi out (worst was 12' seas at 4sec with 25kn sustained and gusts that our anemometer said were at 45) I have some opinions.
1. The ocean is an unforgiving, temperamental mistress that you don't tame, you live with.
2. If you go small boat (length in particular) you greatly limit the number of days you can be out there (the parentheticals are when I call it quits in the ocean except the j30, I never felt unsafe on that).
3. I've converted from "horsepower needed for speed" to "horsepower for overcoming wind and current" when it comes to motors. You may never do 40mph, but you may need the umph because of wind and tides.
4. The biggest factor I PERSONALLY FEEL makes offshore more comfortable is a big V with some draft carrying it aft. The V is more for managing the rollers/chop at speed with the deadrise seeming to make the ride smoother in rougher waters (the sportsman is virtually 0 deadrise while the trophy looks like the bow of most boats (no idea on the actual angle)).

All that to say, I don't think the phantom will be a lot of fun on any day that is not "glass". The ocean side of the keys is deep and fast. Also prone to squalls. If you are a solid captain that knows how to handle a boat in highly adverse conditions then the small bay/lake boats are probably ok. Otherwise, I'd strongly recommend two, more purpose-designed hulls. If you really can only do one boat, I don't know that the PH series is ideal for the ocean side.

I've been wrong before so don't feel bad ignoring me.

BarraMan wrote: ↑Wed Aug 18, 2021 7:29 pm

I strongly recommend an 18' boat. It is a little much for the over 75 crowd,

Huh? I can't let that go unchallenged!

I am not yet in the 'over 75 crowd", but headed that way. I have NO problem launching and retrieving my 22' x 4,000 lb boat solo! Its just a matter of having the right set up, ie drive-on drive-off trailer, a Boat Catch and a ladder on the front of the trailer!

Tis okay. Many old guys throw in the towel, let aone launch n retrieve large boats.

I tend to agree with Jaysen. I am surprised you didn't throw a vote for the LM18 as well.

fallguy1000 wrote: ↑Thu Aug 19, 2021 9:55 am I tend to agree with Jaysen. I am surprised you didn't throw a vote for the LM18 as well.

If it were me... panga all day every day for nearshore. BFP (Big Forking Panga) for off shore offshore. They are well tested, lower power required, easily built, minimalist material hulls. BFP won't be cheap, but it will be fast, stable, and efficient. The weight distribution PangaRon is having is a common problem but that's something you have to address with any hull really (like, I don't know, when someone pulls 800lbs out of the arse end of a Helms 24).

Guys RVC has already said that he already needs a larger boat than a LM18 and its 3 person capacity. So it is a no go. Agree the PH18 will be limited on the outside of the Keys to calm days only. But remember CL took his flat bottom OD18 everywhere . RVC the weight difference between the 60 and 70HP Yamaha outboards is only 6lbs.. These were a brand new design series about 5 years ago. The 50-70 are all off the same block. Hope that answers your weight question.

Tom

Tom,

Your response answers two questions! No doubt the LM18 is a great boat. Also, I did not suspect the PH18 was only for calm days on the ocean side of the Keys so I need to cement this fact in my mind. I am not looking for something like the Panga. The news on the Yamaha outboards is new. I worked with them in 2017 so this is a big deal. I do not think Yamaha dependability can be beat. Obviously, my pdf of dated so I'll download a new one.

Many thanks everyone. This has been a useful learning experience. I will keep reading here. I thought I could treat my freshwater needs and saltwater desires with one boat...I guess not.

RVC here are the data sheets of the 50-70 HP Yamaha's https://yamahaoutboards.com/en-us/home/ ... 0-hp/70-50 You will need to expand the info at the bottom and then look at each one separately. Tom

TomW1 wrote: ↑Thu Aug 19, 2021 4:41 pm RVC here are the data sheets of the 50-70 HP Yamaha's https://yamahaoutboards.com/en-us/home/ ... 0-hp/70-50 You will need to expand the info at the bottom and then look at each one separately. Tom

Kudos to he who can discern a difference between the 50 and 60 besides the listed Hp at 5500 RPM. Difference must be in the programming?

VT_Jeff wrote: ↑Thu Aug 19, 2021 5:12 pm Kudos to he who can discern a difference between the 50 and 60 besides the listed Hp at 5500 RPM. Difference must be in the programming?

They can also do a few things mechanically like the compression ratio or valve timing and duration. Change out throttle bodies so it will take more air and the 70HP states, "Combined with its 16-valve SOHC design and 17 percent larger intakes". That better breathing and little higher RPMs and the gear ratio at the prop could be the difference. I would think they measure rated HP at the prop shaft.

From what I have read, a few of the smaller engines that are only 5 or 10 HP difference, there is a plate under the throttle body that can be changed for a bigger one to increase HP.

Yamaha has a nice smartphone app that allows you to record and download (?) datasets. It may be Android only but that makes no sense. I just own Android. We used it at the marina and it does work well. You have to purchase the dongle to connect to the harness. This may be a 'Service Tool' exclusively so it is possible it is off limits to the general public.

OrangeQuest all good points. As far as the final gear ratio goes, it is 1.85 for the 50 and 60 and 2.33 for the 70HP allowing it to run a larger pitched prop for more speed. The NMMA requires HP be measured at the prop shaft. RVC those data downloads are for dealers only, all of the manufacturers have them. They can tell the dealer everything that has happened and are in a series of code that need to be interpreted.

Well that is it for tonight.

Tom

in high school we took took a family vacation to big pine key and camped for a week. it was awesome. one day we rented a boat, I’m not sure the model or hp. It definately had more of a deep V than the ph16/18. It was an 18 ft boat. My dad asked them do we need to fill up at lunch or anything. the guy said you won’t run out of gas. Ok. off we go we drove that thing all over on the gulf side, had to put the motor up a few times and push it hundreds of yards to get out of the skinny water, just had a blast. then we get the great idea to go on the ocean side, I look at the crappy fish finder find a way over to the ocean side and it was fine just riding along much slower. the. we go to head back a different chanel than we came out, and next thing we know its like 3-4 ft swells, we are going just about hull speed as my inexperienced dad is trying not to stuff us in to the backside of a wave which we did take water over the bow a few times. then we get back to the rental dock and the guy goes to put gas in it and it was pretty much empty. The boat didn’t have a gas guage so we had no idea what actual fuel level was.

long story short, in my experience its two different boats to consistanely go on gulf and ocean sides of the keys