Transom straps on bigger boats

JohnnyAlpha

Member
Sep 1, 2020
44
Boat Info
2004 Sea Ray Sundeck 270
1989 Arriva 2050
Engines
383 MAG MPI w/ Bravo III
I purchased our 270 Sundeck without a trailer and am currently fitting it to the trailer I purchased. I’m also converting the trailer to bunks from rollers in the process. With the amount the transom overhangs the end of the trailer frame, And trim tabs in the way where do you hook your straps to the trailer? The ends of the bunks seem to be the only place that would work but I hate the idea of relying on wood. I tried searching up pictures but none I have found have straps installed.
 
You should still be able to figure out a way to get the strap forward to the trailer frame somewhere. Sometimes you have add a flat bar, attachment eye. Sometimes the straps will go around the side of the boat. Worst case, thru-bolt the flat bar to the bunk. If you can post a few pics of what you have, that would help. Make sure the transom doesn't extend beyond the rear edge of the bunk.
 
Here are some pictures, if I go to the frame it will be pulling more forward than down and the straps will be against the hull. Even from the bunk may conflict with the trim tab.
 

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Pulling forward is fine - it's also still pulling down. There's nothing to worry about from that aspect.

If you can't get the geometry correct to avoid the tab, that's OK. It's not ideal, but it's also not uncommon to have a strap against the outside edge of the tab. Don't worry - I've seen many boats with it setup like that for well over 10 years with no issues. Just put a cloth or old carpet scrap there to protect the strap. The tab will be fine.

Side note... does that trailer have the proper weight rating for the boat? And, will you be able to get the axles back far enough to get enough (5% to7%) tongue weight and equalize the weight on each axle?
 
Thanks again Lazy Daze, I think at this point I owe you a few beers. I guess I’ll have to come around the sides of the hull with some padding or fabricate something to to mount to the bunks.

The trailer has a 9,000 lb GVWR, I’m still working to get the boat up a little further forward 6-12” if I can, but I’ll need to cut and weld the winch post at a steeper angle. Once it’s where I want it I can move the axles, they are just U bolted. I would prefer more like 10% tongue weight 5-7% is a little on the low side, though I have seen that recommendation from some trailer manufacturers.
 
Thanks again Lazy Daze, I think at this point I owe you a few beers. I guess I’ll have to come around the sides of the hull with some padding or fabricate something to to mount to the bunks.

The trailer has a 9,000 lb GVWR, I’m still working to get the boat up a little further forward 6-12” if I can, but I’ll need to cut and weld the winch post at a steeper angle. Once it’s where I want it I can move the axles, they are just U bolted. I would prefer more like 10% tongue weight 5-7% is a little on the low side, though I have seen that recommendation from some trailer manufacturers.
You're welcome!

So that trailer probably weighs somewhere between 1,500 to 1,800 lbs. That leaves you with a 7,200lb, give or take, carrying capacity. How does that stack up once you account for batteries, full fuel/water, gear, etc?

Trust me on the 5% to 7% thing. 10%+ is for 5th wheel trailers, not ball mount. Granted it's better to err heavier than lighter, but somewhere in that 5-7 range is plenty.

Can you post a couple pics of the winch mount/post? Just curious!
 
I guess I’ll have to come around the sides of the hull with some padding or fabricate something to to mount to the bunks.

I used sheepskin seatbelt covers on each of my transom straps where they contacted the edge of the trim tabs. They served the purpose for 5+ years and left no damage on the hull, tab or strap. Easy, cheap and durable.

And the straps kept the trailer in place under the boat in a significant broadside collision—saving a likely rollover of the hull. I’ll never doubt the need for straps, regardless of boat size.
 
On my 300 DA, I strap from a d-ring on the side of the trailer up and over the back of the boat to a d-ring on the other side of the trailer. I use the front edge of the cleat to keep it from slipping back. One large strap instead of two, but it's a pain stepping over it to get in and out while it's on the trailer.
 
I used sheepskin seatbelt covers on each of my transom straps where they contacted the edge of the trim tabs. They served the purpose for 5+ years and left no damage on the hull, tab or strap. Easy, cheap and durable.

And the straps kept the trailer in place under the boat in a significant broadside collision—saving a likely rollover of the hull. I’ll never doubt the need for straps, regardless of boat size.
Sorry to hear about your accident, I hope everyone was ok. Going over the tabs just feels wrong, but would be the ideal way to go for me. Your experience is very reassuring, it’s the emergency situation I’m most concerned about. I have over 2 million miles with trailers behind me, I’ve seen allot on the road.
 
You're welcome!

So that trailer probably weighs somewhere between 1,500 to 1,800 lbs. That leaves you with a 7,200lb, give or take, carrying capacity. How does that stack up once you account for batteries, full fuel/water, gear, etc?

Trust me on the 5% to 7% thing. 10%+ is for 5th wheel trailers, not ball mount. Granted it's better to err heavier than lighter, but somewhere in that 5-7 range is plenty.

Can you post a couple pics of the winch mount/post? Just curious!
I misspoke it’s actually 9400 GVWR. I figure 2000lbs for the trailer leaves me 7400 lbs Sea Ray Says the boat weighs 5800 lbs I’ll call that 6000 lbs accounting for batteries and oil 530 lbs for fuel 200 lbs for water puts me at 8730 lbs worst case. That should leave me 670 lbs for junk, am I forgetting anything?

here’s a picture of the winch post, it’s about 60° now. If I order a replacement From loadrite it looks like they are at 50°, But it’s over $200 To my door and the Small brace is made of angel iron now. I figured I would just grind the welds off and re cut it to more match the bow angle then just hit the welds with cold galvanizing compound. My garage is 30’ deep I’m trying to get the overall length of the whole package under that with the drive off for the winter.

Sorry for the sideways photos it keeps doing that to photos taken in portrait.
 

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Good math - you've got that part covered.

There's no reason it has to match the bow angle. I like the main part of the winch stand. Not super impressed with thinner brackets, but it is what it is.

Move the tongue jack aft of the winch stand to lose some overall length.

Small points here, but... slide the bracket assembly up a few inches to get the cable pulling level. Then move the long-arm brackets forward one or two holes to get the top bow stop as close to touching the bow eye as possible, depending on how much further you can crank the cable in, of course. You may have to get a shorter winch handle. Consider replacing those old bow stop "blocks" with 3-piece rollers.
 
Good math - you've got that part covered.

There's no reason it has to match the bow angle. I like the main part of the winch stand. Not super impressed with thinner brackets, but it is what it is.

Move the tongue jack aft of the winch stand to lose some overall length.

Small points here, but... slide the bracket assembly up a few inches to get the cable pulling level. Then move the long-arm brackets forward one or two holes to get the top bow stop as close to touching the bow eye as possible, depending on how much further you can crank the cable in, of course. You may have to get a shorter winch handle. Consider replacing those old bow stop "blocks" with 3-piece rollers.
Ideally I would like to move the boat up a foot or so, changing the angle should get me around 6”. I can get 6 more inches if I move the whole thing forward like you suggested but I need to relocate the brake line, I may just put it through the winch post mounting plate. The boat will sit a little lower on the trailer when it in its final position, I’ll definitely get the winch pulling straight. And the 3 piece rollers are on the list too, any option urethan vs rubber?
 
How about cutting the excess height off the winch post and mount the winch on the opposite side. Of course you'd have to lay everything out before you start any cutting.;) You could then modify the old winch base and bow stop so the boat could come forward. You'd have to do part of that anyway when you convert to the bow stop rollers. Looks like you could pick up at least a foot just guessing from the pic.
jackstand.jpeg
 
How about cutting the excess height off the winch post and mount the winch on the opposite side. Of course you'd have to lay everything out before you start any cutting.;) You could then modify the old winch base and bow stop so the boat could come forward. You'd have to do part of that anyway when you convert to the bow stop rollers. Looks like you could pick up at least a foot just guessing from the pic.
View attachment 92153
Thank you! That’s a really good idea I hadn’t considered, I’ll have to try and mock up different options with some wood this weekend.
 
On my 300 da, I use two straps from the transom D eings to eyes on the trailer frame. I also use 3 2 inch wide 6000 poundcraychet straps, on across stern just forward of reat cleats, one midship thru those cleats and one on the bow behind the cleats.
 
I have my winch strap on front along with a safety chain then also have a large ~20" long turnbuckle connecting the bow hook to the base of the winch post. Then at the back I have 2 of the smaller rachet straps from the stern rings to the trailer.
 
I also tow a 300
I like the rollers personally
I go over the bow and over the stern
 

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