buiding an L shape rear bench and weight issue advice please

[evolution1985]

G'day all, after such success and GREAT advice from the wonderful people on this forum, I want to post a question that I hope i can get some advice on the more technical side of things.

1997 wellcraft excel 21sx (5.7 alpha)
basically this is the current seating layout that i have.
*twin back to back
*engine box with jump seats that convert to sun lounge

please see drawings

the new layout that i want to make is a full rear sun lounge with storage underneath on either side of the motor for a couple of dive tanks, with an L shaped seat running up the full length of the passanger side with storage underneath for life jackets BCD's an eski, wet suits etc etc. with just a single captains chair for the helm.

Now the question I have is not how to construct it as the wood working required is well within my skill level, nor the trimming as I will get a pro to do it. but with the weight and balance issues. How would i counteract not just the weight of the new seats but also with people sitting on that side. I'd say at a guess allow up to 75 kilos per person and an extra 3 people on that side of the boat. I really don't like the list i get with an un balanced boat, but i figure if the new yamahas and other wake boats can bring it out from factory then there has to be a way to do it?
should i just build the seats allow 100kg for extra kit, weigh them and then add the extra weight in some form under the floor on the other side of the boat? it really has got me stumped.

Any and all help is appreciated. Please understand that this boat was the best one that we could afford and that we could not find one single boat with everything how we both liked it, so hence this project. so Please don't tell me i should have bought one like that. lols If i could have found it in my price range I would have bought it. Although if that was the case I would have nothing to do over winter except snowboard, haha.

 

[smokeonthewater]

Re: buiding an L shape rear bench and weight issue advice please

when you load the boat put heavy gear on the driver's side and light on the other and instruct your passengers on where to sit so as to best distribute the weight then add helm controllable trim tabs.... done deal

Also keep in mind that a thicker and somewhat reclined backrest will move the weight of your passengers slightly toward the center and lessen the offset as their feet will likely reach the center of the boat... you'd want to design a bolster in the front of the seat to keep the derriere from sliding off

 

[evolution1985]

Re: buiding an L shape rear bench and weight issue advice please

I was looking into trim tabs for the boat, as i Get a bit of porpoising as it is, but I liked the idea of smart tabs. will helm controlled trim tabs make that much of a difference? I have never used them. should I offset the weight of the seats into the boat when I build them so that the boat is evenly weighted dry? I have a feeling that after building the seats, coating them in resin, and then carpet and vinyl, i would hazard a guess that they would come in at around 150kgs or more? i was thinking that a lead weight or such running down the other side of the boat would do the trick?

 

[smokeonthewater]

Re: buiding an L shape rear bench and weight issue advice please

No way would I intentionally add weight..... I'd store the anchor and other such stuff on the right and the life jackets on the left... helm adjustable trim tabs can lean the boat enough to scare the poo out of you if you want them too... they make a HUGE difference

You can mount your battery(s) on the right too...... just balance what you have already

Build your seats light.... they aren't Amish oak furniture to last 200 years, but rather they should be lightweight and get their strength from their design with sheer panels and from being tied into the boat in many places

 

[evolution1985]

Re: buiding an L shape rear bench and weight issue advice please

that does make allot of sense, I was planning on using pine, then soaking in resin etc etc. but my thoughts were that the resin and fiber glass would add all the weight. I see what you mean about moving the batteries and anchor etc etc on that side. would it matter if the weight is more to the rear on one side than the other? I used to work on rally cars a fair bit and we did corner weighting. I DO understand that they are nothing alike, but my thinking was that for handling and stability purposes, i would be best to keep the weight even down both sides of the boat?? I also forgot to mention that that weight calculation was for the whole L so I would say that 70% of that weight would be directly over the back of the boat.

See this is why I love these forums, honest discussions without the severe bias

 

[evolution1985]

Re: buiding an L shape rear bench and weight issue advice please

helm adjustable trim tabs can lean the boat enough to scare the poo out of you if you want them too... they make a HUGE difference

now that I didn't know, I knew they worked or obviously people wouldn't use them. I have looked into them and it seems 12x9 seems to be the size to go. I think your right on using what i have and then tabs. I think like most things I have been over thinking things. haha

 

[smokeonthewater]

Re: buiding an L shape rear bench and weight issue advice please

you don't need to worry about corner weighting because boats don't have chassis flex or suspension... while you are adding weight to the rear you are ALSO moving passengers forward... you'll be fine. you don't need to soak in resin... just prime and paint the framing and lay one THIN layer of glass cloth and resin on the flat panels.... abused, it should still be good for 10 years or so... Take care of it and it may well outlive you

 

[evolution1985]

Re: buiding an L shape rear bench and weight issue advice please

thanks again, I do have a bad habit of over doing things a little. I had a nagging thought in my head that any wood should be resin coated. Im not sure where i heard that though. What your saying about the weight shifting with people and everything etc etc does make perfect sense. always good to bounce ideas. So I guess the moment summers over I'll start the build. I was pretty lucky i just pulled the entire carpet out (which was most definitely original) because of wear and tear and the floor is in great condition. I have to hand it to wellcraft, the build quality was far superior of the boats of this age to bayliner!!!! I do have to experiment a little with the design of the rear bench so i don't affect engine access yet still make every thing solid, but now that i know it should be good to go i can get into it when my sons in bed

 

[smokeonthewater]

Re: buiding an L shape rear bench and weight issue advice please

http://www.youtube.com/watch?v=aZ3MDggSWno

 

[evolution1985]

Re: buiding an L shape rear bench and weight issue advice please

yep ok cool, that definitely decides that one for me. I didn't even think to go on youtube to research them. thanks heaps lols the mrs won't be happy as they're about $1000 down under but oh well it looks worth it