PG25 Construction Questions

[serge]

Good evening,

A few questions on the PG25:

Can you eliminate the casting deck and have one flat level deck?
Frame B in the center would be cut down to the BL.

Can you scale it in length only 6% to get 26.5' overall length?
No other dimension change.

Would any wood or glass changes be needed?

Other than frame spacing would scaling length distance of the offset measurements on the hull panels accommodate the needed panel size increases?
Meaning would they fit the newer length?

Or would it turn into a s&*t show?

Is Meranti BS1088 OK to use?

Any benefit to going with Nidacore deck and sole and Divinycell frames?

Thanks,
Serge

[OneWayTraffic]

Some of those questions are for the designer but I can tell you that in general when you stretch in one dimension only you normally screw up the panels, and they don't fit. I know because I asked for my boat, and got the answer I expected.

But since the Panga side panels are cut with straight cuts only, this might be manageable. Small differences in the fit can be sorted with persuasion and some extra glass. The boat is already long for its beam, and will become more so. You might need to add a frame, and will use several sheets more plywood. I do not know if the boat can structurally take that scaling but I suspect it can.

Normally above the deck is entirely to builders preference. The PG20 plans make no mention of the casting deck being structural, but there is a fuel tank there, and this would need to go somewhere else. You would need to leave some frames in the sides, at least 3" unnotched (careful with rodholders etc.)

Meranti BS1088 is ideal, assuming that the plywood actually meets those specifications. Buy from a specialist supplier, or order from this website if American. The epoxy on here is pretty good too apparently.

No idea about frames and soles. I don't see the benefit myself. Easier to use ply.

[jacquesmm]

Good evening,

A few questions on the PG25:

Can you eliminate the casting deck and have one flat level deck?
Frame B in the center would be cut down to the BL.

No please. Where would you put the gas tank? It goes under that small deck and for weight distribution, the tank must be there. If you do that, would be barely able to walk there, the hull is narrow at that point. Last, that small deck is part of the structure.

Can you scale it in length only 6% to get 26.5' overall length?
No other dimension change.

Would any wood or glass changes be needed?

Other than frame spacing would scaling length distance of the offset measurements on the hull panels accommodate the needed panel size increases?
Meaning would they fit the newer length?

Or would it turn into a s&*t show?

Is Meranti BS1088 OK to use?

Any benefit to going with Nidacore deck and sole and Divinycell frames?

Thanks,
Serge

As you guessed, that would create a chain reaction of small problem. and would turn in a big problem. IF you do it anyway, no need to change frame spacing or material specs but don't do it.

Look at the nesting drawing and see the bottom and side panels: you need 4 more plywood sheets just for those parts.

Meranti 1088 is fine.

[serge]

Although not what I wanted to hear thank you for the confirmation that stretching length only isn't a good idea.

[serge]

Few more construction questions when you get a chance Jacques:

1. Nidacore deck and sole OK to replace wood to save weight?
Deck would be thicker to raise floor to enhance self bailing characteristics.

2. Divinycell OK for frames to save weight?

3. If I wanted composite stringers to save weight would you OK and if so what material?

4. I see on the plans how to cut the side panels to get the lines for the PG25S.
I do not see how to make adjustments for the molds and frames for the PG25S.
Are those notes there or are those height increases determined by the builder as the material is being cut?

5. Does the boat require trim tabs?

6. Can the console be moved 24" to 30" further aft?
Batteries and larger fuel tank would be forward.
Better ride further aft.
Notes say 12" OK; hoping another 1' won't screw it up too bad.

Thanks for your time and I look forward to your reply.

Serge

[TomW1]

Serge I would not move the console at all. It has a bad habit of being weight heavy in the stern. 12" may be okay but no more. A 90HP motor has caused problems for a member with the console in the normal position.

Tom

[nightcrawler]

Serge
First dont use Good marine ply for your molds if doing the S. The station a and station g will have to be cut with different heights and it is very difficult to do before the hull is shaped up. I cut the molds as shown and after stiching the panels together it was easy to reach under and add a piece of 2x2 to extend the mold.
Happy building
Roland

[serge]

Thanks for the reply's Tom & Roland.

I'm hoping to get the OK for composite sole, deck and frames to save the weight.
I took the guidance from the ST21 plans and applied it to these to ask the question.
Couple the sole, deck and frame replacement with a composite transom and my napkin numbers show a 200 lbs plus hull weight saving.
Hopefully that's enough to facilitate the console move aft plus I'm sure I'll be heavy on the resin and glass.

Figure the Divinycell H80 for the frames, 3M Reinforced Foam for the transom and Nidaplast H8PP for the sole and deck.
Same or thicker panels as the specified wood for all of them.
Same glass layup for all of them.

I don't think the bang for the buck on stringer replacement would be worth it; only about 20lbs weight savings.

But this boat is a big bigger and heavier than the St21 and moves a bit faster so that is why I wanted the OK before assuming I could swap the composite for wood in those components mentioned above.

Thanks again and look forward to some more replies.

Serge

[fallguy1000]

Moving the console aft is bad for reasons Tom stated.

Reducing the weights aft is wise. The best way to do that is to drop to something like a Suzi 60hp or Yamaha 70 and to move batteries forward of the center of mass.

[TomW1]

Serge by moving the console back you are totally changing the center of gravity. Say the console weighs 300lbs and you weigh 180lbs, that is 480lbs moved a foot behind the COG. You then need to move that same amount of weight forward of the COG some how. Using foam through does not change the COG it just replaces wood with foam and reduces the weight. If you just move the console you will unbalance the boat and water will come in the scuppers at rest. Your scuppers will be higher as the boat will float higher with the foam and the reduced weight and thicker deck.

Serge if you don't hear from Jacques in a couple of days go up to the Questions before building and ask about what size foam you should use for your Panga. Jacques may have been out or may be missing your post. I think it is great idea as larger boats benefit from it, if you can afford it. Using it for the frames, transom and deck should save a couple hundred llbs. Jacques will do you right.

Tom












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