Question on cradle design principles

[Anchor Sores]

I've got a 16' 1967 Sea Ray SRV160 That I am looking to restore. I am going to assume the worst and that I will have to replace the transom and stringers. It looks like the cap will have to come off to redo the transom. The trailer could use some help too.

I haven't had much luck finding info on building a cradle to guard against deformation of the hull while the structural members are being replaced.

Does anyone know of a guide on building a sufficient cradle? Or would anyone be interested in pointing me in the right direction on what and where I should be supporting on the hull of my boat?

Thanks in advance.

 

[stresspoint]

it kind of like " how long is a length of string" , each design boat needs to be supported differently when it is going to be taken apart.
keep in mind , boats are not built to have structural members removed for repair.
so with that said , you need to figure roughly where you are going to retain structure as you take the boat apart and support in those areas.
supporting too much can cause hooks or droops in the strakes , not supporting enough can cause cracks and softness in areas when you are in the process of walking around the dismantled hull.

dismantling a hull for repair or re structure is a job best left to professionals , but these days people dabble in boat rebuilds with the help of forums and youtube .
sorry i cant give better advice as it is up to you to use your own common sense to decide where the supporting needs to be done base on the info i have given above.

 

[Scott Danforth]

I've got a 16' 1967 Sea Ray SRV160 That I am looking to restore. I am going to assume the worst and that I will have to replace the transom and stringers. It looks like the cap will have to come off to redo the transom. The trailer could use some help too.

I haven't had much luck finding info on building a cradle to guard against deformation of the hull while the structural members are being replaced.

Does anyone know of a guide on building a sufficient cradle? Or would anyone be interested in pointing me in the right direction on what and where I should be supporting on the hull of my boat?

Thanks in advance.

each boat is different.

the cradles I have built are simply plywood and 2x4's
cut the plywood to fit the hull every few feet, strengthen with 2x4's

I have also built a cradle on the trailer once. a few 2x4's across the trailer, pizza slice shapped plywood bits to go up to the hull.

take accurate measurements of the points on the boat hull before you pull the cap, use these to ensure that you have it back together correctly.

 

[stresspoint]

ha ha , i too have built a cradle structure on a trailer to support a refurb ,
what a PIA that was to work around , although i will say i got lots of exercise climbing the ladder 500 times a day.
the smashing my shins and knees on light bars and mud guards was no fun either. never again !.
i made a convertible trolley years ago that i just adapt to what's needed with 1x1 square tube and 3/4 plywood , a pipe bender is useful there.
its usually a good days work to organize including the time to lift the boat off the trailer and strip engine and drives /s but well worth the time and effort.

plan the restructure you are doing before you start anything , draw up a grid noting what stringers and floors are going to be chopped out for replacement , any bearers that are going to be removed , etc.
don't make the mistake lots of internet refurb people do and use the keel and chines as the only means of support.
sometimes its nice to build a movable walking platform to drop on the remains of the structure that coincides with your cradle structure ,as walking around a weakened hull can and will cause issues when it comes time to re attach the cap + it also makes life easier when doing the fiber glassing .
its good to see a person asking this question and planning ahead before just going head on into a hull restructure.
as this sounds as if it is your first , this planning will make for a good end result.
enjoy your build .

 

[Anchor Sores]

don't make the mistake lots of internet refurb people do and use the keel and chines as the only means of support.

^This is the type of info I'm looking for.

The boat is currently supported that way on the trailer. I figured it was a starting point for proper support off the trailer.

My workspace is going to be outdoors on uneven ground. I am considering sinking some temporary posts into the ground so I can get the cradle nice and level.

I believe the cap will have to come off to do the transom replacement as well as some repair to portions of the gunwales that are damaged from an apparent tree strike. However, I was wondering if replacing one stringer at a time with the cap still on would help mitigate any deformation of the lower hull. Though I suppose if the stringers are really gone, then the hull would just deform anyway.

As it is the boat seems solid enough aside from the deck. I have read enough times here that the deck is the last thing to rot after everything else.

the cradles I have built are simply plywood and 2x4's
cut the plywood to fit the hull every few feet, strengthen with 2x4's

If I understand correctly these would help keep the hull from potentially flopping open. I am also thinking of putting two or three notched out cross members slightly wider than the hull that would sit on the sheers to keep the hull from clamming shut. Would that be reasonable or a waste of time?