swim platform bolts

timsmith

Hi can anyone tell me, on my 270 vee 2007 model, if the swim platform bolts go right thought the transom? I can't get to my boat for 3 weeks and I would like to book her in for some work but need to know the answer to this cheers

explore7425

I have a 2007 370. I noticed this spring that a lot of the heads on the screws for the supports were gone. I drilled them straight through the transom with a 5/8" carbide bit and then through bolted the supports with stainless steel and nylon lock nuts. That platform is really strong now. You can jump up and down with absolutely no movement. I was shocked at how small and cheap the hardware was from the factory. My platform is exceptionally big and what they used just did not make it. The hard top is a whole other story that I will tell if it comes up. 

Black_Diamond

I know on my 342 they do, would bet yours do too.

timsmith

Yes I guess so also, they have corroded on the water side and need replacing, the guy asked the question at the marina,meh thought also they would but I was unsure , so thanks

Serenity

I have a 320 and replaced mine because they started staining the stern and in the engine compartment. They are through bolted. I am going on three years now and no more staining. ****Now keep in mind-the swim platform is through bolted but the support stanchions are only screwed.

Black_Diamond

replace them with stainless fasteners, no reason for them to corrode. 

TikiHut2

As BD said make sure they're stainless but also know that not all SS is made equally. You typically get what you pay for. The big box (Home depot etc) SS is usually the worst and doesn't fair very well in the long run. Here's a little light reading   (SS QUALITY LINK)   Mike

Black_Diamond

Good point TikiHut.  Many fasteners come from China or other LCC sources where the reality of what you think you bought and what you actually bought are very far apart, poor material quality, not meeting ratings standards, etc.  We often find that where fasteners are sourced can make a difference on whether or not people will buy products. 

Quality fasteners are not cheap!  Look for marine or aerospace quality fasteners.  Stainless fasteners should all be passivated too, this is already done by quality manufacturers but you can do it yourself with a alcohol and nitric acid mix (instructions are available easily).  Also, and especially in sea water,you need to keep the water from getting under the bolt head as the lack of oxygen prevents the 'self sealing' stainless does to prevent corrosion.  Use sealant, buytl tape, etc under the head when to keep water out, not just at the interface of the joint.

timsmith

Hi guys many thanks for all the replies, interesting in that serenity you say the supports are only screwed, i guess you mean the down bars from the platform onto the transom? In which case this is the part I have an issue with. These bolts only screw in right? So if they have corroded could they cause water ingress into the hull/transom? I'm guessing yes in which case I need to replace and let dry out.

Black_Diamond

Always a chance, but take them out and let it dry while out for the winter (assuming you have that issue!).  When you re-install, dip the threads in caulk or 3M 4000 to seal up.  A neat trick is to wrap them in PTFE tape, then dip in caulk, keep the screw from getting glued in.

timsmith

Great advice thanks

Serenity

Timsmith--yes that is the part which is only screwed into the transom. Sorry for the confusion.

I also replaced the thru-bolts along the actual swim platform which ended in the engine compartment. I saw the rust stain running down the inside of the engine compartment-once I replaced the thru-bolts with good quality stainless--I figured I had better replace the supports as well figuring they to are wearing and are in the water all the time since they are below the waterline. I to used 3M 4000.I did not have an issue with water intrusion but better safe than sorry.

I read all the nightmares with owners of all boats having rotted out transoms because of poorly sealed screws below the waterline. I was amazed these were only screwed in. I then saw why-the swim platform is low and the supports ended up about 3-4 inches from the hull. There would be no way of putting thru bolts that low on the transom.