Partially Hollow Core on HC37?

[Dan Begonia]

Does anybody know if the HC37 cutters were built with a narrow hollow void in the side deck core paralleling the cabin sides?

In preparation for doing some delamination work, I drilled about dozen holes in the side deck about 3" parallel to the side of the cabin, stretching from just aft of the lower aft spreader to about 3 ft aft of that. I was surprised that was no core - NADA! - just empty space between the upper and lower fiberglass skins. I dropped an ice pick into these holes and the ice pick hit the bottom fiberglass. Later at night, I enlarged one of the holes to put a small snake-flashlite in to see if I could see light coming up from any of the dozen holes I drilled. Sure enough, every hole had light coming through it.

I then drilled another set of holes paralleling the ones I just drilled, but this time I drilled them about 4" away from the side of the cabin. There I found wood core.

I am dumbounded and perplexed. I thought that deck cores went all the way across the sidedecks.

Anybody know anything about this?

Thanks,

Dan Begonia
1983 HC37C
s/v "Malaya"
San Francisco

 

[Jim Legere]

Gee, that's a real puzzle! I can see where there would be no core in the area of the radius from the deck to the cabin sides, but I would have thought that there wold be something solid there - not air! The guy who might be able to answer your question is Mathurin2 (currently heading south somewhere in the vicinity of New Jersey). He replaced the core on his entire deck and took some good pictures. You can check out some of the story on his blog; the link is given on another thread here in The Cherubini Hunters Forum. Good luck and keep us posted!

 

[Ed Schenck]

Here is the link to Mathurin's deck core replacement: http://mathurin2.blogspot.com/2010/09/les-renos.html . Not sure that you can see an answer to your query though. As soon as they are settled in with wi-fi on their cruise I am sure they will respond.

 

[Mathurin]

You can find the pictures of the job I have on hand here: http://mathurin2.blogspot.com/2010/09/les-renos.html I have nothing else with me. The core doesn't extend all the way everywhere, on cabintop it stops about 3-4 inches inside the original antiskid paint. On the side deck, the core doesn't extend all the way to the cabin side either, and there is no core at the level of the deck to hull joint. Basically there is core section where there portlights are and a void over and below that.

The best suggestion I can give you is to cut about 2-3 inside where the core stops, you can later remove the core in that section using a flat bar and a wire brush on a grinder (works really well).

Here a specific picture of the area you are talking about:
http://2.bp.blogspot.com/_PCv9beR7eY4/TH8yW1u5DEI/AAAAAAAAAFw/Ro7fRmPKWms/s1600/deck7.jpg

 

[Dan Begonia]

Jim,

Thanks for the quick response.

I guess I am naive about naval architecture. Aside from offering a convenient conduit for wiring, what advantages would there be for keeping such a long hollow void on what I would have expected to be a completely cored side deck?

I'm not complaining. With all the wear and tear from sailing in blustery SF conditions and with the several Calif/Mexico coastal cruises she has been subject to, "Malaya"(means "To be free" in Filipino) has given us no reason to regret owning her. The old gal has been comfortable and reliable and takes very good care of us.

Dan

Gee, that's a real puzzle! I can see where there would be no core in the area of the radius from the deck to the cabin sides, but I would have thought that there wold be something solid there - not air! The guy who might be able to answer your question is Mathurin2 (currently heading south somewhere in the vicinity of New Jersey). He replaced the core on his entire deck and took some good pictures. You can check out some of the story on his blog; the link is given on another thread here in The Cherubini Hunters Forum. Good luck and keep us posted!

 

[Dan Begonia]

Ed,

I appreciate your directing me to Mathurin2's link so quickly. I look forward to reading it.

My mind is still boggled by why that hollow core is there. I wonder if this was standard practice in boat building.

Dan

Here is the link to Mathurin's deck core replacement: http://mathurin2.blogspot.com/2010/09/les-renos.html . Not sure that you can see an answer to your query though. As soon as they are settled in with wi-fi on their cruise I am sure they will respond.

 

[Dan Begonia]

Thank you very much for your fast response.

I am impressed by your ambition and skills in dealing with such a major project. At this point, my approach is somewhat modest in dealing with the crunchy "potato chip" noises that I am getting on part of my deck. I am doing the "drill holes and fill with penetrating epoxy technique" to see if that does the trick. There are no soft or squishy sensations when stepping on it and the wood shaving the drill bit produced is dry. So I hope I don't have to go your route and do a major re-coring of portions of the deck. Yikes! Scary thought.

So I take it that when you re-cored your side deck that you stayed with the original design and did not core it all the way to the cabin sides.

That's a great photo of your boat. Elle est tres jolie.

Merci beaucoup,

Dan
s/v "Malaya"
83 HC37c
San Francisco

You can find the pictures of the job I have on hand here: http://mathurin2.blogspot.com/2010/09/les-renos.html I have nothing else with me. The core doesn't extend all the way everywhere, on cabintop it stops about 3-4 inches inside the original antiskid paint. On the side deck, the core doesn't extend all the way to the cabin side either, and there is no core at the level of the deck to hull joint. Basically there is core section where there portlights are and a void over and below that.

The best suggestion I can give you is to cut about 2-3 inside where the core stops, you can later remove the core in that section using a flat bar and a wire brush on a grinder (works really well).

Here a specific picture of the area you are talking about:
http://2.bp.blogspot.com/_PCv9beR7eY4/TH8yW1u5DEI/AAAAAAAAAFw/Ro7fRmPKWms/s1600/deck7.jpg

 

[Finnbardalton]

Voids

I can't think of any reason why a void should occur and suspect sloppy workmanship. I'd drill holes and follow the West System approach to deal with core rot and dry out (if wet alongside the void) and then fill with a thickened epoxy. The void should fill and any holes should mushroom up and provide deck strength. Along the chainplates I'd want as much strength as possible and no voids since the stress load is high. Even aft too since the stress would be distributed there as well.

I've been told by someone who visited Hunter "during the late 80's" that he saw the hull lay up people just tossing some pieces of plywood around as dropped down the cabintop. You might want to explore...

 

[Mathurin]

btw, the original coring method was basically to glue 4in x 4in square pieces of plywood on the top skin and then to lay some fiberblass on top of that. They never took the time to fill in where the plywood didn't join properly, so there are some voids in come areas.

There was no way to recore where there was no core previously. To do that, one would have to do it from inside, which is a big no for our boats. You would have to remove the headliner to get to the inner skin, which be a non sense...

I hope you go with the drilling and filling with epoxy for the good reasons. If the core comes out dry when you drill and that the moisture meter doesn't go crazy when it comes in contact with your deck and you only need to re-glue the top skin to the core, then drilling and filling might be a good idea. If the core is wet and rotten, you will only make it harder on yourself when you got to do the job right because you are still stuck with the same problem in a short while... Just saying, I know how big of a project it's to go the long way...

 

[Brian M H23]

The core is there to provide stiffness in the flat sections where you walk. It doesn't do a lot for the strength, just the rigidity (when compared to the same amount of fiberglass with no core). This area is near enough to the curve that it didn't need coring.

If you really want coring, add rigid expanding foam!

 

[Dan Begonia]

Void

[
Yes, I am following the West System approach. But now I am trying to figure out a way to fill the holes I drilled above the void.

Just out of curiosity, I went to the starboard side deck where I don't have any delamination problems (knock on dry wood!) and drilled holes 3" and 4" away from the side of the cabin. Yep, the same arrangement there too with the void.

It is disappointing to think that the workmanship at the Hunter yard was this sloppy. Some of my other non-Hunter owner friends have made uncomplimentary remarks about Hunter quality, especially the newer models. I sometimes conceded their general point, but always defensively quickly pointed out that the older ones, especially the Hunter-Cherubini's were a superior product. I might have to eat some humble pie. In spite of this, I still like the boat a lot.

Thanks for your other tips. I will keep those in mind as I wade further into this project.

Dan
s/v "Malaya"
1983 HC37c
San Francisco

quote=Finnbardalton;755851]I can't think of any reason why a void should occur and suspect sloppy workmanship. I'd drill holes and follow the West System approach to deal with core rot and dry out (if wet alongside the void) and then fill with a thickened epoxy. The void should fill and any holes should mushroom up and provide deck strength. Along the chainplates I'd want as much strength as possible and no voids since the stress load is high. Even aft too since the stress would be distributed there as well.

I've been told by someone who visited Hunter "during the late 80's" that he saw the hull lay up people just tossing some pieces of plywood around as dropped down the cabintop. You might want to explore...[/quote]

 

[Dan Begonia]

Expandable foam idea

Brian,

Thanks for the insight.

I am going to look into the expanding foam idea. Sounds very intriguing.

Dan

The core is there to provide stiffness in the flat sections where you walk. It doesn't do a lot for the strength, just the rigidity (when compared to the same amount of fiberglass with no core). This area is near enough to the curve that it didn't need coring.

If you really want coring, add rigid expanding foam!

 

[Dan Begonia]

I will indeed proceed with the drill and fill method for now.

Are you familiar with the expandable foam core method that Brian has mentioned?

It's still disappointing that Hunter used what appears to be a somewhat lazy approach to coring. I wonder if it was standard practice with most brands/companies. If it is, then I won't feel so bad.

Thank you for all your detailed insights.

btw, the original coring method was basically to glue 4in x 4in square pieces of plywood on the top skin and then to lay some fiberblass on top of that. They never took the time to fill in where the plywood didn't join properly, so there are some voids in come areas.

There was no way to recore where there was no core previously. To do that, one would have to do it from inside, which is a big no for our boats. You would have to remove the headliner to get to the inner skin, which be a non sense...

I hope you go with the drilling and filling with epoxy for the good reasons. If the core comes out dry when you drill and that the moisture meter doesn't go crazy when it comes in contact with your deck and you only need to re-glue the top skin to the core, then drilling and filling might be a good idea. If the core is wet and rotten, you will only make it harder on yourself when you got to do the job right because you are still stuck with the same problem in a short while... Just saying, I know how big of a project it's to go the long way...

 

[Mathurin]

I hope you are talking about the type of foam they use for rudders, not the type they sel at Home Depot XD. The only thing I would say, if the hollow section has never been an issue, that no marine surveyer ever told you that was a serious problem in the area it's, that there is no oil caning effect... I would not put much tought into it. Even if coring method weren't the best in theses day, they gave themselves a bigger margin, so you should be safe even if your deck is 100% delaminated and rotten as mine was, I sailed in strong winds en never had any problem keeping the tension the wires...

 

[Dan Begonia]

I guess you're right. If it hasn't been a problem for the last 27 years, why would it be problem now? I'll just fill up the holes over the void and leave it alone.

Thanks for all your help.

What is your name BTW?

Dan Begonia
s/v "Malaya"
HC37c
San Francisco

 

[guidera48]

Voids

I have followed this discussion with interest as I too may have to tackle this problem one day. However there are some asumpsions made that I dont agree with.
You did mentioned a space between the upper and lower fiberglass skin. I would assume the lower skin is the inside part of the headliner??

The idea that the shell of the boat should be the same thickness all the way through may be a relic from when boats were made out of solid wood or used balsa core as coring material, making the thickness of the deck pretty much the same all the way, even on the house curves.

We have a fiberglass liner that gives the impression the deck is smooth above it. Should you open the zipper on an Endeavour sailboat that has a vinyl headliner and peek inside, you would see many lumps and bumps where reinforcement materials were used. It is not the same thickness all the way through.

When a Hunter deck was made, the mold was waxed, gelcoat sprayed and layers of glass laid down. First cloth and also chopped,depending an the area and purpose. Plywood was used to re inforce certain areas. Then glassed over. The glass cloth was laid over the plywood squares and rolled tightly on the top and sides of the plywood with a metal roller to make full contact between wood and fiberglass.
Now, if there was too much tension on the cloth or it was not fully edge rolled, there may be a pocket between the layers, at the edges of the plywood, however it cannot be as big as you found.

I believe your botton layer is actually the liner.

These plywood areas were thicker than the rest of the deck. When a molded headliner is applied, there will be areas were the liner does not come in contact with the deck, therefor leaving some spaces. This is not a defect. It was made that way.
When I re bedded my portholes, I found that the inside liner was not attached to the house sides. The porthole screws kept all the layers together.
I just installed yesterday my outdoor shades on all portholes with 4 snaps each. When I pre drilled my holes, the top holes found wood, however the lower holes were just through glass.

I will leave to others to judge wich construction method is the best method. We love our boats dearly, but should remember they are not Swans or Wauqiez.
It is what it is.

Jose

 

[Ed A]

wait just a second here

I let this go long enough for everyone to sound off about something they dont know a lot about and the few who do understand what the deal is here.

These boats a great boats! They are not fully cored or balsa cored, im glad they are not. the space between the deck liner and head liner in the sides of the cabin were never designed to be fully cored. Frankly with the materials used it is a very very common application.

The deck and the liner for that matter are designed to take conciderable load as independant units and when needed are mated together. The boat is a chevy of ford in car terms. Great cars not mercedes.

That being said the blocks in the deck areas are different. the loads on and flex on the deck is totally in another direction. Wood blocks were an approved method of construction used by most builders of the era.

the idea behind it is to stiffen the pannels to give more rigidity.

So all that being said. I would not worry a second about the lack of wood in the boat, instead i would embrace it. If you want to add foam, wood, divinicel, or epoxy have at it, Just weigh it before you start adding hundreds of pounds of material to the boat so far above the waterline because it is very easy to convert a great boat to overweight out of balance top heavy block house that wont sail worth crap.

The guys that designed and built these boat were skilled knowlegble and competent. They have lasted 40 years with tremendous performance and are still sought after boats for all they are.

I think is pretty dumb for someone to belittle it especially those who know what these boats have proven by years of performance.

Much of the problems with these boats are common in almost every builder out there.

ta da now ill get off my perch and stay out of it.

 

[Jim Legere]

Gotta agree with Ed A!

The fact that my decks are still solid after 27 years indicates to me that Hunter knew what they were doing. Ever look at a floor truss? Lots of space and air in them, but they are more ridgid than a solid floor joist. The deck of the Cherubini Hunter is like a 3D floor truss - nuf said.

 

[Ed A]

a couple of other thoughts,

The deck to chainplate concept is not valid. All the load on chainplates it bolted directly to the inside of the boat not to the deck. if you look at the chainplate closely there is a cover with small screws to cover the hole where the chainplate goes thru the deck and bolst to a bulkhead, the real strength there is carried by the fiberglass backing on the bulkhead not the plywood. again the wood is just to have a place to lay the glass and material to bolt thru.

 

[Ed A]

I wish i was a bit better at my typing,, bolts. not botls.

any way.

As for using foam. Polyuretane foam is difficult to use properly. I do not reccomend it be used to repair or fill voids in the deck unless it is put in as a sheet material.

The 2 part foam kits have very strick guidelines for use. (another reason builders did not like to use it. The two parts have to be mixed very carefully by volume. The temperature and humidity in the area you are working is critical, Mixing time is very critical. they type of mixer is important. All that said if you dont do it right you end out with the worlds biggest mess. it sticks to everything it touches and espands for quite some time after it begins to set. It taks special equipment to properly fill a rudder for example. if you dont get enough in you get a void anyway and if you get to much liquid in the foam will expand and break the rudder, dont ask how i know.

I saw a crew mix up a batch to insulate an ice box. the inside liner of the ice box was a separate part. The plan was to mix the right amount up and pour it in then insert the liner for the ice box then wedge it in place with 2x4s till it kicked. humm. looked great when it went in. the boat creaked alot and a good bit came out the top and made a mess, they though that was it untill i pointed out the 12" diameter 6" high buldge in the side of a new boat... bad day to say the least!

Foam will expand and force the deck and liner apart. you can not contoll where it goes and what will happen in a deck.

Oh the memories!