Making a Fiberglass Platform - Tips Please

OK. This summer's project is to make a fiberglass platform for my dad's Crownline. It's a 225 BR & for some reason, they don't offer the platform for that model yet - it's in R & D. How should I start out? I know the logistics of mixing & laying fiberglass, but what about the structural integrity?

Jory,

I would suggest your best bet is to have a wood inner structure that is sealed and completely fiberglassed and painted. If you want to have a completely fiberglass platform, then it pretty much requires makeing one from wood and cloth to get a shape and them making a mold from that part, then making your platform. To make a mold you will need to consider the shape so the part will pop out of the mold once it is laid up. You will also have mold release agents for this process but you can also make a gel coated finished product. If you check out the link in my profile I have a link to tips on building a speaker box which may give you some insight for materials and some methods for this project. You could shape the wood structure with SS brackets as part of the shape prior to glassing it which would then allow you to bolt it to brackets on the boat and not affect the wood which is sealed in the figerglass. Just some thoughts if I was going to do this.

Good luck.

you might wanna try these guys there from az and they do killer work swimplatforms.com

Consider the safety aspect as well. I've seen 5 people standing on the edge of a swim deck before. 5 x 180 = 900lbs. They probably had a center of gravity about 20 inches out.

Torque = distance * force
Torque = 20” * 900lbs
Torque = 18000 Inch/pounds of torque
18000/12 - (Convert to foot pounds)
Torque = 1500 foot pounds of torque! Basically, at 1 foot away from the boat, the deck is experiencing a load of 1500lbs.

The safety is two fold, first you wouldn't want the deck to break with jagged edges that would injure people as they fall into the water – especially if it’s an I/O. Secondly, you wouldn't want the deck to separate from the boat and take a section of transom with it, sinking the boat. You should be able to calculate out your loads at most of the attach points for your bracing.

Good luck, and post pictures. I really want to see how you tackle this!

Thanks for the link Jim. I think I came across that one last week when browsing the forum. Didn't even occur to me until you refreshed my memory.

Craig, I definitely don't foresee 5 people standing on the back unless we are arguing about who gets to ride first! But, you do make a good point. That was why I was wondering about the structural integrity of such a project. Who knows, I emailed swimplatforms after reading above for a price quote, so if the price is right, I may go that route. My guess is that I am going to end up making my own though. I've seen other companies selling them for a pretty penny & at this point in time, I just can't afford that.

Hey Jory,

Obviously from Craig's calcs, you can see WHY they are so expensive...a failure can be catostrophic!

This is an I/O? Do you need to allow for the "leg" when it's in the "up" position?

And FYI - "fiberglass" is a VERY broad topic, anywhere from polyester to epoxy then there's cloth, matt, a woven roving (not to mention all the "exotics") - each are specific for the purpose intended...if you're using wood as a "core", go with epoxy.

(Message edited by wesgardner on May 08, 2006)

(Message edited by wesgardner on May 08, 2006)

I understand that a failure could be devastating, especially with it being an i/o, but after the aftermarket platform manufacturers have their design, there really isn't any more r & d that should continue to keep their prices so high, right? I guess boats are like motorcycles, the parts are a killer because they know if you want them you will buy them regardless of the price.

There should be plenty of clearance from the way it looks. It is a pretty tall boat so clearance really isn't much of an issue, but one that will be figured in when the template is made. I am intending to use epoxy resin as I already have quite a bit from a past glass project.

Jory,

Drawing from my very limited fiberglassing experience , I would suggest using Woven Roving to get your initial build thickness. You can get this stuff up to 48 ounce. Once it's resined, it's hard as a rock. I'd expect that you'd need 5-8 layers for a swim deck.

Here's an example of it - though it doesn't give you a good idea of how thick it really is:
http://www.fiberglasssite.com/servlet/Detail?no=4

Don't forget the upward force on the swim platform due to the water underneath in your torque calculation.