Asking for your expertise on boat trailer

Larry Connally

New Member
Sep 3, 2020
26
Delta Colorado
Boat Info
Sea ray 340 sundancer 2002
Engines
MerCruiser mx 6.2 mpi
The trailer in question is a magic tilt aluminum triple axle under a 02 sea ray 340 sundancer. Just purchased this boat last year and took the boat to a nearby sea ray dealership for some repairs to the keel and some other encounters. I get the boat all checked in with service desk and head home (45 minutes away) and service manager gives me a call. Says they will lift boat and do repairs but highly recommend a new trailer. He says this one doesn’t support the boat adequately. This trailer is only good enough to put boat in water and take out. Not 7B07752C-29E5-440F-AAD0-F457B8302AAE.jpeg good enough for 5 hour drive to lake Powell. Only $18K for a steel trailer.
Last year we made 4 trips to lake Powell after buying the boat. I hate the bumper pull. But it did as well as could be expected for a bumper tow. Boat did well. Repairs to boat aren’t trailer related. But I don’t want to ruin our new-to-us baby. Rating tag on trailer supports the boat. I will try to attach pics but the basic description is 2 bunks that are 4” x 10” or so and seem to be in good support positions but I definitely don’t have a lot of experience in a boat this big. 7B07752C-29E5-440F-AAD0-F457B8302AAE.jpeg
 

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Larry, What is the rating for each axle? Is the picture how the boat is actually loaded and ready to go? Do you have a picture of just the trailer by itself? JC
 
And some photos of how the boat contacts the bunks

and VIN capacity label if legible
 
My first impression of your first picture is that the tires are overloaded. Too much squish in the side wall for a properly inflated tire.

What is the load capacity of the tires? It’ll be printed on the sidewall.
 
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Trailer capacity is a combination of all the components involved.
your starting at 13,000 lbs dry weight and 11' 5" beam (so oversized load permits)
If you have full fuel another 1,500 lbs (try not to tow full)
Plus any gear you are carrying.
Always dump the water tanks before towing, just more weight.

So when you say the trailer can handle it, the tag would need to say around 15,000 carry capacity, and around 18,000 GVWR, tires Load Range E, axles 6000 minimum.

And I upgraded to electric over hydraulic brakes. Truck upgraded to a 17,000 2" XD class V (I dont need the full 18,000 you may)
my 300 is 11,000 dry, I dump the water but with 1/4 tanks of fuel and gear I weight in at the scales at 12,500 for the boat, 3,500 trailer (mine is steel) 16,000 GVW. My trailer came with load range D tires, but that was marginal so I upgraded to Range E 3,640 per tire, so my axles can handle 18,000 and tires could handle 21,840.

You are always limited by the lowest component so for me the hitch at 17,000 is my limit, but I'm at 16,000
 
Larry, What is the rating for each axle? Is the picture how the boat is actually loaded and ready to go? Do you have a picture of just the trailer by itself? JC
I can’t find a pic of trailer by itself and it’s all still at the dealer. The previous owner had a mix of load G and E tires. I replaced all tires with load G.
 

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Yeah, that's fine, so it just may be the bunks need to be reset to provide better support...
 
Trailer capacity is a combination of all the components involved.
your starting at 13,000 lbs dry weight and 11' 5" beam (so oversized load permits)
If you have full fuel another 1,500 lbs (try not to tow full)
Plus any gear you are carrying.
Always dump the water tanks before towing, just more weight.

So when you say the trailer can handle it, the tag would need to say around 15,000 carry capacity, and around 18,000 GVWR, tires Load Range E, axles 6000 minimum.

And I upgraded to electric over hydraulic brakes. Truck upgraded to a 17,000 2" XD class V (I dont need the full 18,000 you may)
my 300 is 11,000 dry, I dump the water but with 1/4 tanks of fuel and gear I weight in at the scales at 12,500 for the boat, 3,500 trailer (mine is steel) 16,000 GVW. My trailer came with load range D tires, but that was marginal so I upgraded to Range E 3,640 per tire, so my axles can handle 18,000 and tires could handle 21,840.

You are always limited by the lowest component so for me the hitch at 17,000 is my limit, but I'm at 16,000
These pics are prior to making the tires all load G. 8 lug wheels. Unfortunately I can’t find a good clear pic of boat on the bunks or trailer by itself
 
Yeah, that's fine, so it just may be the bunks need to be reset to provide better support...
Ok. Now I’m worried why the dealer went straight for the jugular and pushing a $18K trailer. Concerns me about the work we have already authorized
And then new bunks could be added if it needs more support, right?
Thank you for your guidance
 

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Ok. Now I’m worried why the dealer went straight for the jugular and pushing a $18K trailer. Concerns me about the work we have already authorized
And then new bunks could be added if it needs more support, right?
Thank you for your guidance
Jugular is right on the money!
 
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Correct, I have rollers that support all over, but the concept is like blocking the boat up.
You block up the keel and out toward the chines.
You want the weight to be well supported by the trailer also, don't want to put so much weight in one spot you bend a cross beam as you bounce down the highway.

upload_2021-2-18_10-37-22.jpeg


Here is a good example the outer bunks are right over the beams, and have angle cut to mach the hull, and have braces so they cant be squeezed outward. Plus a center section to protect the keel while loading and support it.
Now the angles all have to be right so your not sitting across a strake/chine flat against the hull. This one looks like for a fairly flat stern not a lot of rise.

upload_2021-2-18_10-41-13.jpeg


Here is one with the bunks attached to the cross frames but out near the beams, this allows more angle in towards the bow if needed. Then up forward you see a keel guide for the bow.
 
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As others have stated its all about axle ratings at this point but the overall build is important too. Brakes, tires, overall construction and how trailer fits your boat. To be honest the trailer looks like it would be ok to me BUT with knowing the above my op is useless. Pictures and VIN capacity will help. Good Luck. JC
 
And watch out for thru hull fittings and tabs and such.
BAD - what if you forgot to raise the tabs?
upload_2021-2-18_10-53-32.jpeg


GOOD - vertical support under a primary chine.
upload_2021-2-18_10-53-12.jpeg
 
The trailer seems to be rated properly. 100 psi for tire pressure indicates at least load range G and that would be appropriate for the weight. Couple thoughts - I am with hughespat57, I suspect the dealer is questioning bunk position not being properly centered on the keel. this boat is heavy enough that there should be some keel support like his photos shows. That is rare bunk configuration as most boat trailer bunks I have owned and seen dont position so well around the keel. Likely the heavier the boat the more important keel support becomes. So to address this, simply add another set of bunks to your existing trailer at or near the keel. Its not as easy as it sounds though, will take a 1/2 day likely with a boat hoist available. Also would recommend cutaways in bunks to support strap hoisting not just for this but future launch/load to keep trailer salt free for as long as possible. If your only fresh, not as big a worry. I cant tell from your initial description if you have two or four - Assume 4 bunks so I would add two more centered around the Keel. This you can do to the current trailer you own likely. One other comment, I work for environmental company with a marine mapping division that hauls boats (big heavy ones) from Seattle to Miami and everywhere in between. They started with aluminum welded frames 20 or so years ago. They worked fine for first few years but then with all the vibrations, starting cracking welds. Became worse as time went on. They no longer buy welded aluminum frames in leu of bolted frames. You will still have loosened bolts but weld crack issues is resolved. weld cracking can be catastrophic with heavy boat loads.
 
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And some photos of how the boat contacts the bunks

and VIN capacity label if legible
So this is the best pic I have at the moment. Front arrow is a roller low on front of keel. Second arrow is a support with a plastic guard on it. The third mark is a 4” x 10” bunk that runs to the back. It is positioned under a chine (if I’m using the terms right) and when the boat is on the trailer, the boat only makes contact at the high bow roller (at the winch) and these two bunks (only 1 bunk on each side of the boat). The lower keel roller and the other support with the plastic guard make no contact when loaded. Definitely not as supported as some later posts
 

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Let's recap for those that didn't see the VIN photo:
19,850 GVWR trailer
17,000 Carry Weight
7500 axle ratings x3 = 22,500
Load Range G tires 3,700 (G/126) x6 = 22,200

Boat
13,000 dry
14,500+/- loaded
So trailer specifications are NOT an issue...

As to current support/bunk setup:
two forward keel supports
two aft bunks for the Aft 1/3 or more (the aft third is where most of the weight is, beamest, engines, drives, fuel batteries, generator, etc
This is quite typical to what I have seen.

So other than maybe adjusting the bunks for a better "fit" to the hull there should be no issues.

At this point I would be going back to the Service Manager, with these numbers in hand.
Ask "Oh I need a better trailer? What is better about this new trailer you are proposing?"

Unless there are frame cracks or some failure of the current trailer it makes no sense.
 
Thank you for all your help. I’ve only been able to leave a voicemail for the service dept manager but I’ll keep you posted on the progress (hopefully)
 
So I can just contact them to get the right fit bunks for that trailer to fit my boat?
First thing I'd do is ask them if they're necessary and talk to them about what this "service manager" said. Likely BS, but the manufacturer can confirm it. Your tag really says it all, but for the warm fuzzy it might be nice to hear it from them.
 

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