FS18 OFFSHORE

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jacquesmm
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Re: FS18 OFFSHORE

Post by jacquesmm »

Quick remark: the 450 kg weight listed for the PG20 should be named trailer weight, not hull weight. It includes everything with the boat on the trailer, engine too. The PG boats are light for their length.

Beware of seaworthiness legends. I have been to many parts of the world where the locals use poorly designed and built boats because nothing else is available. Local sailors go out because they have no choice but that does not make those boats better. I have seen this first hand in Senegal (Casamance), Haiti, Belize and more.
Many long and narrow boats exist because their hull shapes are extrapolated from dugout canoes with raised sides. In Jacmel, Haiti, 1980, I have seen freighter canoes of up to 40' running 50 miles offshore with 10 HP. That does not mean those are great boats. They are crap handled by extremely good sailors who have no choice.

Narrow boats are easier to plank, less bending.
Exceedingly narrow boats tend to stuff their bows in waves, that is why they have those raised bow planks like the Mexican Pangas.
Bolger designed a few very narrow boats, 30 years ago. Most are river boats but I remember one about 28' long and around 4' wide, open boat, outboard powered, planing hull. I heard of only one builder and he was not enthusiast about the result.

About your project: just stretching and raising sides of a flats boat may be dangerous. A loaded long boat is a beam subject to bending and twisting, take that in account please.
The bottom panels are subject to slamming and what is sufficient for a flats boat (protected waters) will not be adequate for an offshore boat.

Stretch one of my Pangas if you want and keep the weight low but there isn't much to save in weight. You will have to add frames and some sole/deck to resist bending and twisting. I am not convinced that it will be a good boat. The panga proportions are right.
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Re: FS18 OFFSHORE

Post by OneWayTraffic »

jacquesmm wrote: Tue Oct 11, 2022 12:50 pm Quick remark: the 450 kg weight listed for the PG20 should be named trailer weight, not hull weight. It includes everything with the boat on the trailer, engine too. The PG boats are light for their length.
...
Stretch one of my Pangas if you want and keep the weight low but there isn't much to save in weight. You will have to add frames and some sole/deck to resist bending and twisting. I am not convinced that it will be a good boat. The panga proportions are right.
Hi Jacques.

Two questions:

1. If the Panga 20 was built to plans, kept very simple and tiller steered with a 20hp, what speed would one expect?

2. Could it be built with lighter materials assuming that it was again only powered with a 20hp and used recreationally rather than as a workboat? By lighter I mean using 6mm plywood on the bottom panels instead of the 9mm specified, and 9mm for decks etc instead of the 12mm specified? This would somewhat improve performance with a 20hp I'd expect.

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Re: FS18 OFFSHORE

Post by pedroe »

jacquesmm wrote: Tue Oct 11, 2022 12:50 pm

About your project: just stretching and raising sides of a flats boat may be dangerous. A loaded long boat is a beam subject to bending and twisting, take that in account please.
The bottom panels are subject to slamming and what is sufficient for a flats boat (protected waters) will not be adequate for an offshore boat.
Hi Jacques. Thank you very much for your input.

So the problem of an fs18 offshore with raised freeboard is only the structural integrity? Assuming that it would be reinforced to support such loads offshore, is there any other issue that might be dangerous? I mean regarding stability or other parameters that I don’t know about.


What is the hull weight of the panga 20?

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Re: FS18 OFFSHORE

Post by fallguy1000 »

The Panga will not plane with the 20hp, but it will run at displacement speeds and someday, you can upgrade the motor. If the 20hp is not a long shaft or 20", then you need a new motor because going to sea with a 15" shaft is very dangerous. A few waves come over and you sink...unless you build a full height transom in front of the splashwell, I suppose..

The top speed of the Panga with a 20hp engine will probably be hull speed or 7mph...it may get a bit higher, say 10, but based on the study plans it is going to stall out below the hump.

This idea of raising the freeboard of a skinny, flats boat to make it safer is a horribly incorrect notion.

To take your example a bit further, consider a canoe. Make is strong enough for a 20hp engine on the transom and raise the sides a foot. What have you created? A really easy way to tip over in a boat.

What you continue to do is called square pegging. You have a square peg in the 20hp engine and you want to build a boat suited for it, but also suited for offshore work which is the round hole.

People fish offshore all the time in kayaks. The problem is they are severely limited in ability, but they are also extremely mobile and quick to turn into a wake or head sea. The FS18 was never designed to quickly turn into a large boat wake.

Another thing you could do is build a 15-16' wider hull design and not worry about planing speeds. I fish in offshore conditions in a 16' skiff all the time. I always plan to come home on following seas because head seas are a nightmare and I get soaked. The OD16 and the PH15 would be good options and the PH15 wpuld plane with the 20hp under light loading and a light build, maybe speeds around 15..
My boat build is here -------->

viewtopic.php?f=12&t=62495

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Re: FS18 OFFSHORE

Post by OneWayTraffic »

I would again suggest the Fs17. It can run 20mph with a 20hp if built light. It also comes in low sheer, standard and high sheer versions and the hull weight is under 150kg if kept basic and open. With benches and if you have glassing experience the total weight could be under 300kg all up. It’s also capable offshore, as this was designed in from the start. It’s modelled on a well known Simmons sea skiff that was taken well offshore.

I have the plans and a planing analysis (right in front of me) published by the designer. The analysis states that it will go 26mph with a displacement of 1055lbs and at 20hp (14.03 after losses at the prop). I don’t think you will match these theoretical figures but even if you get close it will more than meet your program.

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Re: FS18 OFFSHORE

Post by fallguy1000 »

OneWayTraffic wrote: Tue Oct 11, 2022 9:21 pm I would again suggest the Fs17. It can run 20mph with a 20hp if built light. It also comes in low sheer, standard and high sheer versions and the hull weight is under 150kg if kept basic and open. With benches and if you have glassing experience the total weight could be under 300kg all up. It’s also capable offshore, as this was designed in from the start. It’s modelled on a well known Simmons sea skiff that was taken well offshore.

I have the plans and a planing analysis (right in front of me) published by the designer. The analysis states that it will go 26mph with a displacement of 1055lbs and at 20hp (14.03 after losses at the prop). I don’t think you will match these theoretical figures but even if you get close it will more than meet your program.
I still have no idea why anyone is recommending the FS for the SOR.

The suggestion meets the engine well, but not an offshore boat. I wouldn't go out a mile on Lake Superior in the FS17. Maybe shoreline; that's it.
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Re: FS18 OFFSHORE

Post by OneWayTraffic »

Because the designer explicitly states that it is offshore capable is why. Excerpts from the study plans:

https://www.boatbuildercentral.com/Stud ... _STUDY.pdf

The design goal was a capable small skiff in the style of the Simmons Sea Skiff. The boat had to be economical and simple to build, in the spirit of our OD16 and OD18, with the same seagoing capability.

This is an easily driven hull with 25 degrees deadrise at the cutwater and almost none at the transom: 3.5 degrees. Enough vee to take a good chop offshore but sufficient beam at the chine for good stability. The hull depth is 26" in the middle, the bow is 37" high. The stern is very buoyant thanks to the high motor well bulkhead. This boat will not be swamped over the transom.
In all versions, the sole is well above the waterline and the cockpit is self-draining. Note the high designed displacement: it places the waterline just below the cockpit sole at level trim. Most FS17 will never be loaded to that point and their draft will be less than the 7" listed.
During the design, our message board had some very active discussions about the Simmons Sea Skiffs, and I couldn't help comparing them to our new design. We wanted at least the same offshore capability as the Simmons Sea Skiff and with the design complete, we can guarantee that our FS17 is a more able boat.


I wouldn’t choose to take it out in rough weather, but I’m pretty sure it would get me home. I can’t speak for Lake Superior but Pedro has given us no information about where he plans to take it. I chose to build the C17 for more capacity but I wouldn’t say that my boat has more capability. Built right and handled well that little Fs17 is as capable as the Panga20. I have the plans for both and in my view seaworthiness between the two is a coin flip. The Pg20 has a little more length but the Fs17 will be more nimble with a 20hp and that matters. Both have almost identical height at the bow, progressive deadrise and a fine entry. The Fs17 has a lot more flare on the sides giving a lot more volume up high than you would think

In NZ I’ve seen 4m boats go out and catch Marlin. Size helps but it’s not the most important thing.

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Re: FS18 OFFSHORE

Post by OneWayTraffic »

More on the Simmons Sea skiff that the Fs17 was based on.

https://www.timelessboatworks.com/newbu ... seaskiff20

Boats like these are somewhat out of fashion with modern high hp outboards but still just as capable (more actually) as they were back then.

Size isn’t everything. My C17 should be more able than the 11ft Dinghy I had before but I took that offshore, got caught out several times in 25-30 knot winds, and waves breaking around the boat. It was wet, uncomfortable and I wished I was not out there. But I got in. It helped that it wasn’t possible to put enough water or people in the boat to sink it. It also helped that there was so much side buoyancy that I could pull the bung, let it fill and jump on the gunnel without taking a swim.

Some photos. The mountain is on the West coast of the North Island of NZ. I’m 10km offshore but twice that to the ramp. Not many days like that there which is why I was out there.
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pedroe
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Re: FS18 OFFSHORE

Post by pedroe »

OneWayTraffic wrote: Tue Oct 11, 2022 11:52 pm Because the designer explicitly states that it is offshore capable is why. Excerpts from the study plans:

https://www.boatbuildercentral.com/Stud ... _STUDY.pdf

The design goal was a capable small skiff in the style of the Simmons Sea Skiff. The boat had to be economical and simple to build, in the spirit of our OD16 and OD18, with the same seagoing capability.

This is an easily driven hull with 25 degrees deadrise at the cutwater and almost none at the transom: 3.5 degrees. Enough vee to take a good chop offshore but sufficient beam at the chine for good stability. The hull depth is 26" in the middle, the bow is 37" high. The stern is very buoyant thanks to the high motor well bulkhead. This boat will not be swamped over the transom.
In all versions, the sole is well above the waterline and the cockpit is self-draining. Note the high designed displacement: it places the waterline just below the cockpit sole at level trim. Most FS17 will never be loaded to that point and their draft will be less than the 7" listed.
During the design, our message board had some very active discussions about the Simmons Sea Skiffs, and I couldn't help comparing them to our new design. We wanted at least the same offshore capability as the Simmons Sea Skiff and with the design complete, we can guarantee that our FS17 is a more able boat.


I wouldn’t choose to take it out in rough weather, but I’m pretty sure it would get me home. I can’t speak for Lake Superior but Pedro has given us no information about where he plans to take it. I chose to build the C17 for more capacity but I wouldn’t say that my boat has more capability. Built right and handled well that little Fs17 is as capable as the Panga20. I have the plans for both and in my view seaworthiness between the two is a coin flip. The Pg20 has a little more length but the Fs17 will be more nimble with a 20hp and that matters. Both have almost identical height at the bow, progressive deadrise and a fine entry. The Fs17 has a lot more flare on the sides giving a lot more volume up high than you would think

In NZ I’ve seen 4m boats go out and catch Marlin. Size helps but it’s not the most important thing.
Thank you to everyone that is helping!

One way; some times the designers are very optimistic regarding their boats performance with low hp. Or they are very optimistic regarding the final hull weight. After all most of us are not professionals.
Looking at the fs17 beam, it is difficult for me to believe that a 20hp engine will be enough, even if the final hull weight ends up being what the designer specified. I need to do some research in this forum to find out if anyone put a 20hp on a fs17 and reported the performance.



Regarding the location, the boat will be used in Portugal- Algarve. The city is Faro. The surrounding is a 60km lagoon connected to the sea called Ria Formosa.
Most of the time I fish inside the lagoon, but when the weather is good I would like to venture offshore 5-6 miles maximum. The connections from the lagoon to the sea are through inlets. Those inlets can be tricky and the time to go through must be chosen. For example in full moon when the tide is going down is not a good ideia. Tide amplitude is around 2.5m-3m, so the current is significant.
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Currently this is my boat. Built 17years ago (I was 20). It is perfect inside the lagoon. It has the 20hp Suzuki that I would like to use in the next boat. Several times this boat has pass though the inlets to the sea, when the conditions are right, but I never venture more them 100-200m in the sea.

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Re: FS18 OFFSHORE

Post by OneWayTraffic »

I wrote a lengthy reply but it got deleted. The FS17 is 1.5m max beam on the bottom panels. 1.6 max at the water line. It’s not as wide as you would think. This is based on the plans not guesswork. The weight quoted in the study plans is for an open boat with nothing. You would probably add benches etc but it will always be lighter than a panga built similarly. The panga just has heavier scantlings. Again based directly off the plans.

Edit: I see that that is the same motor I had on my Smartwave 3500. I could get up on plane with a load of 400kg, though it was more comfortable at 300kg. The smartwave had a plastic hull, and it was very draggy. Weight for weight a FS17 will perform better.

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