GT27 Sea Keeping ability

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fallguy1000
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Re: GT27 Sea Keeping ability

Post by fallguy1000 »

Here is a quote from Jacques.

Be good to newcomers on the site please. Our goal needs to be to help people build boats. If Jacques said, "I", that means himself as a seasoned operator with 50 or 60 years of helmsmanship. He did not advise this boat be used that way.
jacquesmm wrote: Thu Mar 27, 2008 3:04 pm The GT27 should be kept near to shore in good weather only.
The boat will perform well on rivers, ICW, in the Keys etc. but not to cross to the Bahamas or cruise the Gulf of Mexico.

You could do all what you describe with the GT27 except crossing the Gulf or the Gulf Stream. You can go from the Mississippi to the Keys through the ICW with occasional small trips outside.

I am prejudiced and do not consider any outboard boat as an all weather boat. Fast planing outboard boats can go offshore because they can get in protected waters in a short time if the weather changes.
And they will take bad weather much better than the GT27.
Consider the GT27 to be an houseboat that will take a chop much better than most other houseboats but it's still in the houseboat category.
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OrangeQuest
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Re: GT27 Sea Keeping ability

Post by OrangeQuest »

These plan designs are intended for the home builder and not a commercial shipyard. I would guess a commercial shipyard would have a naval architect on hand and engineers all along the way making sure all commercial standards are met on any designs. As far as giving specifics about a boat and what it can handle, that again would be out of the hands of the designer, since they are in no way supervising anything being done to the build or if the design plans are followed. And to much exact information in what seas a boat can handle would open the designer to a lot of liability. And with society's mindset now days of "put the blame on someone else for my actions", that would hold true as blaming the designer for any mishappens the builder or the helmsman may have with the boat. The op of this thread is expecting information a commercial shipyard would expect from a naval architect with a firm understanding "contract" that the boat be build to very exact design specs and there will be documented proof, again just guessing, that the design was followed.

I just watched a show of a ship being build, there were a lot of engineers involved in supervising its construction and a no one was allowed to go onto the next part of the build till an inspector signed off on the construction. We are talking one bulkhead to the next. From the description the OP gave of his career, he is from that type of environment. Welcome to the private sector! No one supervises or inspects anything you do or if you are following any plans to the letter. The plans you buy from these designs will give you where to put frames, strings, skin and the thickness of the wood needed to do so. Also let you know where and how to reinforce those same things. If the plans show a cabin, it's possible it will show a few different outside shell of said cabins, framing and recommendations on where to put the helm station, head and so on. But it is still up to you to do it and figure out how. You may decide to use a lot cheaper glue than epoxy to hold everything together, that is your choice even though the plans say otherwise. You may want to move a frame a few inches from the plans and again, your choice. In the end, you take on all liability on making it seaworthy.

If you are not only the builder but the skipper as well, then you make the decisions on where and what conditions YOUR built boat will do. How many times have you seen an ocean going vessel have structure failure in rough seas, even though the vessel should be able to manage the conditions the Capt. put it through? Who was a t fault? The designer, the shipyard or the Capt.?

Also, a skipper can take a boat into rough seas and capsize or get swamped. Another skipper in the same exact boat, exact same conditions and the boat may not take on too much water. Who would be at blame for the first skipper losing the boat? Could it be a design flaw because it was said, on paper and by science, it could manage those conditions.

Remember, we live in a time where if you order hot coffee, there HAS to be a label on it that it is hot and even then, someone will want to sue someone else if they spill it and they get burned.
"that it isn't just an ordinary sort of boat. Sometimes it's a Boat, and sometimes it's more of an Accident. It all depends." "Depends on what?" "On whether I'm on the top of it or underneath it."
A. A. Milne

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Re: GT27 Sea Keeping ability

Post by TomW1 »

Mizzzenman, Jacques in most plans asks professionals to contact him for design adjustments for production boats. He also attaches that the boat is designed to ABYC standards. Don't know why he did not on the GT27 other than that it is an older plan. I would also put a little larger motor on that houseboat due to its windage. Maybe a 40HP, not much difference in fuel use at 7-8 mph but more power if needed.

Good luck on your build!

Tom
Restored Mirror Dinghy, Bought OD18 built by CL, Westlawn School of Yacht Design courses. LT US Navy 1970-1978

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Evan_Gatehouse
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Re: GT27 Sea Keeping ability

Post by Evan_Gatehouse »

To expect that a small boat like this would have an operating envelope any more detailed than the description is just not accurate. Maybe you could point me to boat plans for amateurs that have such a design envelope stated.

Not sure why you're comparing it to a class operating envelope that is used for design of classed boats. These vessels are so far outside of what a class rule would consider that it's just not useful to even mention them in the same breath.

Ian Farrier said about his F-27 that it wasn't designed to cross oceans - but people have done so and while he doesn't recommend it, they usually do OK. That's about the same level of accuracy as Jacques comments. It's more about the operator than the boat. It's designed for the hull pressures of planing speeds with a 25 HP motor but the low bow restricts its seakeeping in waves. It isn't going to capsize in 3' beam seas unless you do something stupid. Other than that I can guarantee there is no secret design envelope that Jacques used - I sure don't use one for the little boats I've designed for this site either.
as required by all major boat design certification bodies
- which would those be? Other than CE and that is for production boats. And they don't certify the design like a class society.
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Re: GT27 Sea Keeping ability

Post by OneWayTraffic »

I've spent a bit of time trawling through Jacques comments on the GT27 and other various boats. He does say once (back in 2006) that he might take it across the channel in good weather or the gulf stream in good weather. He's also pretty clear that the boat is not designed for this and should not be built for this. But if you know the boat very well and are an experienced skipper the boat won't kill you. The GT27 can be built with a bigger than 25hp outboard, which might reduce the crossing time. He also states in the same post that people take kayaks across oceans, but nobody calls them ocean capable boats.

In every other post I have seen he reiterates that the boat is designed for nearshore use only in good weather. I find that clear, as someone that has taken a D category boat 10km offshore an exposed coast multiple times. I am still around though once or twice I was beginning to wonder.

I would agree with the choice of DS23 or 25.

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Re: GT27 Sea Keeping ability

Post by TomW1 »

OWT I totally agree with you except I believe, you meant the DE23-25. We all have to remember that Jacques is an accomplished open ocean sailor and what he can do most of the rest of us would not attempt. Evan has made a circumnavigation of the globe. If you do build the GT27 follow their wisdom and stay close to shore. The Gulf of St. Lawrence down can be dangerous so have an anchorage planned that you can get too quickly.

I don't know what the step down is in the DE25 but you could make the deck flat for your dad and make the head room 6'2" in the cabin without the boat looking ugly. It would be a much better handling boat in rougher conditions and wind states.

Good luck on your build.

Tom
Restored Mirror Dinghy, Bought OD18 built by CL, Westlawn School of Yacht Design courses. LT US Navy 1970-1978

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Evan_Gatehouse
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Re: GT27 Sea Keeping ability

Post by Evan_Gatehouse »

In Belize I took our FB11 with a tiny outboard out in 6 seas to guide somebody through a pass in the reef. I wasn't worried in the slightest though the folks in the sailboat were slightly worried for me. I think it's mostly all about knowing your boat and how it will deal with whatever conditions you might face.

I wouldn't take a GT27 across the English Channel in anything stronger forecast than a F3 (7-10 knots wind) AND the weather pattern was stable. The English Channel is not known for afternoon thunderstorms that suddenly arise :). 25 land miles is only a few hours at 7 mph. I'd do it in a sea kayak with the same sort of forecast (well stronger winds for the kayak if they were astern!)
english channel.jpg
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Re: GT27 Sea Keeping ability

Post by rick berrey »

He has worked as an Engineer in the marine industry for 10 years , worked on yachts for the past two , and has a design he tried to post here and couldn't . When designing my house i did all the design work and engineering math myself for a concrete structure and wanted someone to back check me . I have never had a problem getting an Engineer or other Professional I have worked around in my industry to lend a helping hand , as was the case on my house design . So I am sure in the position he is in he can find someone to help him finish up his design , and provide him with the numbers he wants if he is not capable as an Engineer in generating the numbers himself . Most people understand what inshore means

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Re: GT27 Sea Keeping ability

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rick berrey wrote: Fri Dec 09, 2022 10:57 pm He has worked as an Engineer in the marine industry for 10 years , worked on yachts for the past two , and has a design he tried to post here and couldn't . When designing my house i did all the design work and engineering math myself for a concrete structure and wanted someone to back check me . I have never had a problem getting an Engineer or other Professional I have worked around in my industry to lend a helping hand , as was the case on my house design . So I am sure in the position he is in he can find someone to help him finish up his design , and provide him with the numbers he wants if he is not capable as an Engineer in generating the numbers himself . Most people understand what inshore means
Huh?
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Re: GT27 Sea Keeping ability

Post by rick berrey »

Evan , I have the plans for the sk21 Sea Kayak , I might get around to building it one day , I'm glad to know you would cross the English channel with it , :D

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