GP21 Hull Ride / Behavior Questions

[serge]

Thanks TomTom.

I'm leaning towards the Panga 25.

But the load capacity of the GP21 is very attractive.

So is the draft.

Hopefully Jacques will comment on the chop handling aspect along with the low speed almost planing performance of the GP21.

If the GP21 is either on or off plane then that really sways the argument to the Panga 25.

If the GP 21 can plug along at semi planing type speeds without plowing thru the water then it'll just further confuse the debate.


Serge

[jacquesmm]

All the comments above make sense.
Those boats, Panga 25 and GP21 are very different. Despite the shorter length, the GP21 is a bigger boat but the hull shape is very different. The Panga will run smoother in a formed sea. The PG25 will have a smoother transition from displacement to planing speeds, a lot less bow rise but same trim once on plane. With sufficient HP, the GP21 will run faster in calmer waters but the PG25 will keep running when the sea builds up at a time when the GP21 will have to slow down.
The Pangas will handle semi displacement speeds better than production boats of the same size but will have less top speed.

Sea state definitions are subjective unless you use the Beaufort scale and that does not apply to our small boats.
Tampa Bay can be unpleasant with a small chop. I can't begin to put figures on that: a low 1' chop with a short period will be more unpleasant than 3' waves with a long period. Then, the idea of what is unpleasant will vary with the individuals or even their age and experience. An experienced skipper will slightly change his course or speed and run smoother. He may also play with trim tabs. Sorry for the imprecise wording but I can not quantify what a small chop is, it is subjective.

[fallguy1000]

If you build the Panga, the one thing I seem to remember Ron saying is that the boat was a bit wet, so I'd pay attention to that and build in some good splash rails.

So funny to hear Jacques mention different people's attitudes about wind. My experience is the older the guy; the less he tolerates a breeze.

[serge]

Thanks for the reply Jacques.

I try and stay off the water when the winds or waves kick up.
My 70 plus mile one way Middle Ground trips are done.
Until I can afford a 47 Freeman and the fuel bill.

I realize the Panga 25 will be a better ride than the GP21.
I'm just trying to quantify how much better to see if the floor space and load carrying sacrifice is worth it.
I know it's almost impossible to put down on paper.

If built the sole will be raised and spray rails will be installed.

[fallguy1000]

What about the abaco23?

[Johnston]

I know that this is an older thread - but I read through it and was curious regarding the comment on load capacity of GP21 vs PG25.

I was always under the impression that a panga is designed as commercial craft to be loaded very heavy and still remain reasonably efficient because of its length and shape and that it operates well at semi-displacement speeds.

Certainly here in Gabon they are loaded to the absolute maximum with goods like bananas and they still seem to get around at reasonable speeds.

Please correct me if I am wrong.

[fallguy1000]

I know that this is an older thread - but I read through it and was curious regarding the comment on load capacity of GP21 vs PG25.

I was always under the impression that a panga is designed as commercial craft to be loaded very heavy and still remain reasonably efficient because of its length and shape and that it operates well at semi-displacement speeds.

Certainly here in Gabon they are loaded to the absolute maximum with goods like bananas and they still seem to get around at reasonable speeds.

Please correct me if I am wrong.

The immersion data is what you really want.

The immersion of the GP21, a shorter and fatter planing craft is 578#/in. The immersion data for the Panga 25 is 521#/in. But the comparison is unfair because the GP21 is a much shorter boat. So, technically, a GP21 can handle more load for the same waterline. And the mechanics are simple really. The GP21 has much greater waterplane and thus displacement.

All that said boasting the GP21, the Panga25, for her narrower beam should be better on fuel for any given load. She has higher l/b ratio.

But for fishing, I'd prefer a scaled GP21 vs the Panga because it is a more stable platform. PangaRon is a contributor here and runs a Panga he loves in California. The boat does very well in rough weather and this is also probably due to less beam; although I do not know the deadrise details either and have to get going here..

[OrangeQuest]

If dead rise were the same on both, I would pick the long skinny over the fat short all day long in rough weather. I'd pick a hull that would cut through waves more than ride over them. Anchored up in rough seas the short flat will respond a lot on every wave and in all directions whereas the long skinny would be more gentle response to the same wave action and may even have the bow deep under from time to time. Short fat may be a drier ride in rough seas, but the body would feel it at the end of the day. Also, when a big wave hits the side of a short fat the boat would have an increase chance of capsize whereas the long skinny would not be at the same risk for the same size wave.

[TomW1]

If you are comparing the GP21 to the PG25, you are comparing an inshore boat to an offshore boat. The GP21 is basically a nice inshore/lake/bass boat that is very well designed for those functions. The PG25 can go well offshore and still handle heavy seas within reason and the skipper's skill.

Tom