Dinghy Davits – Dom’s Ramps and Alex’s Mounts

[Alex F]

I have to admit that it took me a while to make up my mind regarding the ramps for my application. I’ve read most of the threads and got good response from few CSR members that built their own. I have to say that I was inspired the first time I saw Dom’s thread (I think it was in 2007 or 2008) when he posted his design using Weaver Receivers brackets and his “sandwiched attachment” the mounts for the ramps. I saw few other people successfully replicating the idea and some came up with similar idea using other materials. Although, I liked Dom’s davits very much there were two things that didn’t convinced me to do the same replica:

1. I don’t have a shop that can weld those brackets for me.
2. I didn’t like something like the Weaver Receivers on the swim platform to be toe stabbers for my kids.

So, I decided to come up with my own design for the brackets that mounts on the side wall of the swim platform. I have to say that one of the hardest parts was filing those brackets to fit the curved platform side since the back side is not straight as on many other models. Thus, making this setup for those models where the back of the platform is straight will be a piece of cake.

Parts and Tools:
1. I used cardboard to create a template using Dom’s ramps as my baseline guide.
2. I’ve purchased 2 pieces of starboard 34” x 9” x 1” from eBay for about $80 or so.
3. I’ve purchased a new filing set for $15-$20 and set of blades for my jigsaw.
4. Set of stainless still bolts, washers and nuts.
5. Drill with set of bits.
6. Table saw for cutting large and straight parts.
7. Stainless still bolts, nuts and washers.
8. 4200 sealant.
9. U-shape brackets for tie-downs.


Building Process:

1. The first thing I did was cutting the cardboard to create a template using Dom’s ramps dimensions. But, since my ramps have different attachment to the mounts I had to cut the bottom of my ramps differently.
2. I’ve pre-cut some larger parts using table saw and for everything else I’ve used jigsaw. To make the final edges I’ve used the filing set.
3. I’ve pre-cut the mounts but had to finish them only while being by the boat. The difficult part was to fit the mounts flat on the curved platform. I’ve used jigsaw to cut the angle and the rest was just manual effort to create curved shape.
4. I was debating as to what would be the better approach to install the ramps, while the boat is on hard or in water. I decided that in water would be the better option since I’ll be able to have the dinghy lined up right there by the platform. So, I pulled the boat slightly out of the slip to leave just enough room for the dinghy to line up by the platform and was able to accurately install the mounts while making necessary adjustments right on the spot. It worked very well.
5. Before attaching each piece to the platform I prefilled each hole with 4200 preventing any water to come in contact with open fiberglass.
6. After the mounts were attached I attached the U-shaped brackets, which I’m using for tie-downs to secure the boat without drilling any more holes.

Here're some pictures:

The total cost for material and tools was about $100-$120 and it took me roughly a full day or so (although I did the project during few nights spending couple of hours here and there). The installation also took few hours.

My dinghy rig weights approximately total of 130-140lbs between the 4hp motor and the dinghy. After using my davits with the dinghy a full season travelling for hundreds of miles in very different open ocean conditions I can say that I’m pretty happy with the way the setup is holding up.

I hope that this is timely thread that will give other folks an idea on how to make very nice davits setup by spending just over $100.

Cheers,
Alex.

 

[another escapade]

Alex , great job and great pictures.

 

[Larry]

Nice job!

 

[hack4alivin]

Wow, that is a great job Alex.

It looks almost identical to the mounts that I purchased, but for what I paid for them….. Holly cal way too much for what it is. I like the way you did the pivot mount, mine is mounted horizontal on the swim platform instead of vertical like the way you did yours. My only concern is the “***” where the pin goes through; it looks small for the load. Did you have any concern that this would break when lifting the dinky?

 

[Alex F]

Thanks guys.

I guess there're few advantages I can point out comparing to some other installation I saw using the SS weaver receiver mounts:

1. The only parts that can rust are the bolts, nuts, washers and the SS pin with the safety wire. Everything else will stay the same for the life of the rig. I won't mention the name, but I've seen 1 year old weaver mounts that looked the're ready to be replaced. It's obviously SS quality issue and has nothing to do with the installation.

2. The weight of my ramps. My ramps turned out to be very light, which makes it very easy to handle and store.

 

[tdschafer]

Alex,
Awesome post & very timely!!!! Thanks for taking the time to do it. you make it look so easy that I think I might even be able to do it!!!:thumbsup:

 

[Alex F]

... My only concern is the “***” where the pin goes through; it looks small for the load. Did you have any concern that this would break when lifting the dinky?

Bill,

I knew this question will come up as it is what might look like the "weekest point". The reality is that if you do it right it's not a problem at all. What I mean is:

1. The amount of "meet" in that part is not much, but it's enough to do the job as all it's doing is creating a pivit point for the ramp to swivel up/down. The biggest seller is the 1" think strataboard, which is very strong.

2. I cut the U-shape openning in the mount to fit perfectly and keep the ramp tight preventing the ramp from moving side to side.

I have to admit that when I did this initially I had plan A, B and C, just in case if my original design doesn't work.

So, the original ramps looked like this:

Then, after using the davits for about over a month or more and doing few trips, I've noticed that the weight of the dnighy in the stern (with the motor on and the floats and the underseet starage filled with bunch of stuff) are pressing too much only on the back ramp and one day it was tilting a bit. So, came up with the perfect fix for this which is insert a triangler shape wing that keeps the ramp solid in place preventing any tilting motion.

After implementing this fix (my plan B) I only enjoyed using the ramps and never had to correct anything esle.

IF you ask what's my plan C? This was the worst case scenario, in case if the pivit point wouldn't hold I could always get the weaver receiver mounts and convert the whole thing to how Dom's setup is.

Alex,
Awesome post & very timely!!!! Thanks for taking the time to do it. you make it look so easy that I think I might even be able to do it!!!:thumbsup:

Thanks Todd,

You're right, when we see things in ready stage they always look easy, but the truth is it requires a lot of detailed work, patience and of course being able to do it. There are several stages where you can screw things up. Since most of us (including myself) will do the ramps for the first time it’s better not to think about time at all. I just did most of the prep work at home, couple hours here and there when I had the time. Then I also had to spend extra time during the installation.

As with anything, there’s always a trade off. If you don’t want to pay for the existing product you’ll have to invest your time and efforts.

I personally like doing some projects just for the fun of it and see if I can do it, especially if it’s something different. I’ve never seeing anything setup like I did, so it was an interesting invention in a way.

 

[my3sons]

Nice set up. I like how the triangular piece helps distribute the load.

 

[Go Aweigh2452]

Very nice set up and well thought out... Nice when someone spends the time coming up with a solution and does an excellent installation. Nice write up as well. :smt038

What did you use to put your dink registration on?

 

[Havana Shamrock]

Alex, I can only assume you mean my brackets? Just because the material says Stainless steel doesnt mean it wont rust, this mistake or misconception happens often. Stainless Steel is rust resistant not rust free, so after a few months of water exposure the S.S. brackets developed surface rust, which can be removed easily with scotchbrite cloth. I do not want to "sand" these brackets every week so I have re-done the "arms with 1" starboard and am having the brackets powder coated white, from a metal finisher In hopes that it will slow the process down. I like the way your system looks simple,clean, and effective you know sometimes we over think things when all we have to do is slow down and maybe back up a step or too, I believe my system works well but maybe a little more complicated than it needs to be. Good job!!

 

[Alex F]

..
What did you use to put your dink registration on?

Thanks Doug.

I just purchased some special glue from marine supply (I was told it's specifically for this application), but it's a junk. The number plate was periodically coming off and I had to add some glue thruugh out the season. At the end of the season I just took them down and am looking for better solution.

.... Stainless Steel is rust resistant not rust free, so after a few months of water exposure the S.S. brackets developed surface rust, which can be removed easily with scotchbrite cloth. I do not want to "sand" these brackets every week so I have re-done the "arms with 1" starboard and am having the brackets powder coated white, from a metal finisher In hopes that it will slow the process down. I like the way your system looks simple,clean, and effective you know sometimes we over think things when all we have to do is slow down and maybe back up a step or too, I believe my system works well but maybe a little more complicated than it needs to be. Good job!!

Joe,

I'm not a SS metals expert, but I think (not sure, just thinking loud) there must be different grades where higher level cost more and lasts longer and takes much longer to rust. My assumption is based on different SS hardware I saw over the years. Thus, I'm not sure if it's really necessary to powder all SS mounts, I think that some people had better luck with theirs. I remember last time I saw Dom's setup and mounts looked just fine. Well, maybe he polished them before the raftup, but I don't think so.

I didn't mean to imply that there's anything wrong with the approach on using Weaver Recievers, in fact I think it's very successful setup many have used. So, I'll just say that my setup is simpler, less expensive and just something different.

 

[Havana Shamrock]

Alex, I'm not sure about the grade of S.s. either but even the s.s hardware i bought has started to show rust. the screws are 316 s.s. i'm not sure what grade i used for the brackets but my friend who welded them says it's a very good grade, but i'm not sure if he means in strenghth or rust resistant now.well all i can do is try to make it look nice and work efficiently as best as i can :huh:

 

[Alex F]

Joe,

I have similar experience with 316 grade of SS and wish for better results. The bolts and nuts we get don't last too long before developing some rust. Actually you can see that the bolts that hold my mounts have slight rust developing only after one season. We have number of SS parts that SR installed, e.g. engine hatch hinges, cleats that remain rust free. This might be the higher grade of SS or they might have special coating applied. In this case you may look in to SS coating wich will look great instead of white.

May be someone can clarify for us.

 

[HUMPH]

You always want to use grade 304 in marine environments. This costs more but has much better resistance to corrosion.

 

[Go Aweigh2452]

Actually, 316 is the highest grade stainless we can get in screws and deck hardware that I am aware of. 304 would show signs of rust and 316 would not.

I think some of you may have been told your stainless is 316 and you probably paid for 316 but got 304 instead. There is no test I know of to check if it really is 304 or 316 steel with the exception that a poor 304 will be attracted to magnets and 316 never will.

I have seen 304 stainless anchors rust but never seen a 316 anchor rust.

Your stainless flatware is made using 316 and it never rusts.

 

[Alex F]

Doug,

What you said makes sense. I think that things like nuts and bolts are 304, which explains why they rust much quicker.

Joe, I think that your receivers might actually be made of 304 instead of 316, but I'm not sure how we can prove it other than taking it back to the supplier ans show the condition after only one year. You can take pictures of the engine hatch hinges that look as new after many years.

 

[Havana Shamrock]

I agree , the S.S hardware on the boat looks great after all these years , today i removed the weaver mounts from the platform and found rust under them ,from the S .S. plate i used to build them up, well i wont be using that again, i cleaned them up and they look new again, I wonder what grade they are? I'll speak with the metal finisher during the week to see what is the best thing and look for my mounts. I apoligize for hi jacking the thread from Todd I'll let it go now.

 

[Go Aweigh2452]

I agree , the S.S hardware on the boat looks great after all these years , today i removed the weaver mounts from the platform and found rust under them ,from the S .S. plate i used to build them up, well i wont be using that again, i cleaned them up and they look new again, I wonder what grade they are? I'll speak with the metal finisher during the week to see what is the best thing and look for my mounts. I apoligize for hi jacking the thread from Todd I'll let it go now.

Hey, I think it is all good... I think a lot of people probably got some good info on this.

Not like we went political on it... (which is refreshing)... :thumbsup:

back the the thread... I am still very impressed... looking forward to the next swim step photos that use this design...

 

[Alex F]

Joe,

I can give you one more idea besides investing in to another set of SS Weaver Receiver mounts. You can try to switch to something similar to my idea of the mounts. You might have a concern about existing holes in the platform, so I'd suggest to adjust the mounts to reuse existing holes by installing them horizontally flat on the platform, just like you had your SS mounts.

Honestly, I think that even if you have to start from scratch it might cost you less to build the same setup I did (remember the material cost me only about $80). I cut the board in such way that I had plenty remaining material to build the mounts. This could be an over kill in your case, but just another idea. But, I tell you that the building of SS mounts was #1 reason I steared toward different design.

 

[expressboy]

I have been looking at the Dom's Davits and others and want to build a set... I have a couple issues/thoughts though....
I have a h.p airdeck zodiac that the aft section of the bottom has very little deadrise... it is almost flat. and it also has a couple runner skegs so I figure the davit will need to hit the hull in front of those

I am also concerned that the davit needs to be " thicker " to spread the load some... has anybody ever done a set out of wood... Ipe, Cumaru, tigerwood.. solid tropical hardwoods not plywood.. I have all of these at my disposal and a nice bright varnished set of tigerwood davits would look pretty nice..
Thoughts??
EXPRESSBOY