Choosing the right outboard for my dinghy

[C lectric]

If the boom itself is a single tube then consider adding a tensioner on top about 3" to 4" above the actual tube. It could be welded on of plate standoffs and a rod atop the standoffs.

Or it could be a cable with a turnbuckle for tensioning although you will still need the standoffs.

THe tensioner should be brought all the way down to just above the deck pass through.
I am not suggesting this will get you double the capacity but should add another 100 #. A good fabricator should be able to help.

As for the engine if you figure the 9HP Tohatsu is workable then get the 15hp for the same weight.

I did not have quite this problem but when I was buying our O/B for our dingbat I let my wife talk me into the 6HP Yamaha engine. It would not quite plane the boat with the two of us. I rued the decision untill it was stolen 2 yrs later, no I didn't do it, and then replaced it with the 8hp Yamaha at the same weight. World of difference.

 

[SteveK]

Dinghy and engine will be lifted by my boom onto the flybridge rated at 125 kilos (275 Lbs)

Someone educate me at how you measure the boom load, also is the boom part of the overall 125 kilo?
My thinking is that one end of the boom is secured to the pole and the other end is attached to the pulley top of mast and to dingy lift point. Is the compression of the boom this 125 kilo?
I would think the weak link is at the mast top pulley which IMO is carrying the weight/load, which in turn anchored to the deck.

 

[SteveK]

From a 2018 discussion that I agree is another weak link

I have a 1988 GB 46. Having looked into this in the past the GB published capacity is 300 pounds. However looking into it further the limiting link on my boat is the two forward shroud connections to the fly bridge rail. I am in the process of fabricating new shroud connections that will be tied onto the outside of the cabin. Overall I would suggest you look at your shroud line connections.

 

[SteveK]

From 2016

Hi Bob,
About your question for the weight limit on the mast and boom to lifting a RIB tender :

In 1986 I visited the Grand Banks shipyard (American Marine LTD) in Singapore. On this occasion, I asked many questions to the technicians of the shipyard, one of my questions was the weight limit of the lift capacity with mast/boom.

The answer I got was very clear : the woody 42' GB have mast and boom made with wood, the weight limit of the lift capacity with wood mast/boom was 200 kg maximum (440 pounds). The fiberglass 42' GB have mast and boom made with ALUMINUM, the weight limit of the lift capacity with wood mast/boom was 150 kg MAXIMUM (330 pounds).

With both wood and aluminum mast/boom they told me it is very important to check the wire tension of the shrouds of the mast before operating a lift.

Fair winds,

Olivier

 

[Ski in NC]

With that limited hoist capacity, consider getting a lighter dink and like a 4hp motor. Sure, you can't go fast, just take your time and enjoy.

There may be a way to upgrade that lift capacity, but that can't be evaluated over the net.

Alternative is to tow the dink around most of the time, then when making a long crossing take motor off first with hoist, then lift dink. We tow ours around mostly, but for open water and high speed, motor comes off and we drag dink into cockpit by hand.

 

[Datenight]

Tigs,

We had Trick davits on the NP 39. The dinghy was a #120ish North Atlantic aluminum hull and the motor a 15 hp Tohatsu 2 stroke. Don't remember the weight of the motor. I could pull it up myself but was much easier if Diane helped.

Thanks for the reminder Dougcole!

Rob

 

[Group9]

I'd go for the 15 HP. But, the important thing is to not get one that's too big for you to handle. On our first cruise, we took an 11 foot Whaler with a 25 HP Mercury.
Pros: You could load that thing down with people and still get on plane. With just me in it, It would do over 35 mph (scary to do).
Cons: Every time I moved that motor from the boat to the dinghy, I hoped I wouldn't hurt my back.

They next trip, we took two outboards. A Mercury (Tohatsu) 3.5 HP, and a Nissan (Tohatsu) 9.8. (which would plane the Whaler, but barely) We ended up putting the 3.5 HP on 90 per cent of the time, because I could easily one hand the thing on and off the dingy. And, we found out, we didn't need to go that fast in the dinghy anyway.

All three of those motors were two strokes. I don't care for 4 stroke small outboards.

 

[OldDan1943]

I'm not sure how import duties would apply and I'm not suggesting you break any laws....but you could buy a 2-Stroke ouboard in the Bahamas.

https://www.hbsmarine.com/two-strokes

Only if you declare it.

 

[FlyWright]

I would definitely recommend getting the max hp the dink will support if the load isn't too much. I regularly demate my 15 hp Merc 2-stroke from my dink to lift the dink onto the swimstep for transport. Using my Garhauer lifting davit (150 lb limit), the entire launch/mount motor or detach motor/load dink process takes under 10 minutes and I don't even break a sweat. The motor travels on a fixed transom motor mount next to the dink on the swimstep.

 

[Crossroads]

Yes, here's another endorsement of the Garhaurer lift. I've got one in the corner of the aft cockpit for the 9.8 and a modified one on the FB deck for my PT11 sailing dinghy.

 

[rsn48]

I suspect you know this, but many of the manufactures smaller hp engines are Tohatsu in drag. So my Merc short shaft 9.9 is Tohatsu. Here is a post I grabbed from another forum, it discusses Merc, but Mariner as well uses Tohatsu.

Tohatsu is Japan's oldest outboard manufacturer. Mercury Marine is a division of Brunswick Corporation and many of the smaller Mercury Outboards are just rebranded Tohatsu Engines. ... In addition, the entire line of Nissan outboards are rebranded Tohatsus.

 

[TBill36]

Unrelated to engine selection, but so yourself a favor and buy a bimini top for your dingy. You can get them for about $100 off the internet. I've been cruising the Bahamas for the last 30+ years and it's one of the best things I've bought.

 

[sunchaser]

Which ever one you get, one with EFI is best. Don't forget Suzuki.

+1

 

[caltexflanc]

Unrelated to engine selection, but so yourself a favor and buy a bimini top for your dingy. You can get them for about $100 off the internet. I've been cruising the Bahamas for the last 30+ years and it's one of the best things I've bought.

I second this many times over. Especially down in the tropics and sub-tropics.

Boatcoversdirect.com is my vendor of choice give almost 14 years of regular use and abuse. A lot more than a 100 bucks though, for top quality fabric and made to fit your specific boat model.

 

[Tigs]

Like to thank all that contributed to this thread really helpful. With that said I'm going with the 9.8 Tohatsu or 9.9 Yamaha. Weight is important to me that is why I didn't go with a 15HP and from what many people told me with a 9'6" aluminum rib dinghy (108Lbs) I'll have no problem planing with a 9.8 or 9.9.

What I won't do is try to lift it all on my fly. I e-mailed Beneteau and they downgraded the lift from 125 kilos to 105 kilos weight limit, that's only 230 pounds. Not going to waste my money trying to reinforce the boom. But I will host the dinghy and motor separately like for instance when crossing the gulf stream or if I need to travel in messy weather. (great suggestion from a member)

I might install a motor bracket on the stern and a simple davit system to bring up the dinghy. That trick davit system that was suggested looks pretty good and simple.

So now it's which make Tohatsu or Yamaha, (Yamaha 6 pounds heavier, 200$ more I'm guessing a better re-sale) Tohatsu 5-year guarantee and until the end of this month, Yammie is doubled from 3 to 6-year guarantee.

I think the deciding factor will be the closest servicing dealership where I live and the possible service areas in the Bahamas for the appropriate engine.

 

[Tigs]

Yes, that is what we have with some mods to make it stronger. I also use a block and tackle to haul the tender up onto the cradles. Our tender is pretty big.

define "mods to make it stronger" lol

also, what do you figure is the total weight of your dinghy, engine, etc.
I think I will hit the 210-pound mark with everything.

The last question what do you figure is the height of the top of your swim platform to the waterline. Guy told me that's really the deciding factor if it will be hard to pull up or not. (higher off the waterline tougher to pull up.)

thanks much

 

[henrymei]

Check out PrestoMarine hydraulic lift for swim platform. It is robust and May be a solution

 

[Traumagas]

Personally I would go with the 15 hp. Just because you have more hp doesn’t mean that you have to use it but when you need it you will have the power. And the weight difference is negligible.

I agree plus once in the Bahamas you may want to do some sight seeing and leave the boat . Rather then moving the trawler for a great port. 15 hp all the way
Suzuki’s. Also a good choice . If you wait till getting to Bahamas you possibly find a 2 stroke as they have yet to ban them if that’s something you are considering

M/ V persistence

 

[FANCY-FREE]

We have been to the Bahamas and noticed that there are more Yamaha outboard engines than any other make. We have a Yamaha. We did not need any parts, but I would suspect that because of the amount of Yamaha's if you did need parts they would be easier to find. Go with the 15 HP. They don't weigh more than the 9.9.

Enjoy your trip. A great place to go.

 

[Dougcole]

define "mods to make it stronger" lol

also, what do you figure is the total weight of your dinghy, engine, etc.
I think I will hit the 210-pound mark with everything.

The last question what do you figure is the height of the top of your swim platform to the waterline. Guy told me that's really the deciding factor if it will be hard to pull up or not. (higher off the waterline tougher to pull up.)

thanks much

We have a Highfield 340 Classic, listed weight 157 lbs, with a DF 20 hp Suzuki, listed weight 97 lbs. So 254 lbs for just boat and motor. We usually leave all the stuff in it (fuel, gear etc) so it is likely in the 300 lbs range.


It's a little hard to explain the davit mods we made, but I will try. The trick davits are constructed with what appears to me to be Starboard, which is great from a corrosion standpoint, but suffers some strength issues. Each set of davit arms is bolted to two starboard "cams" which form the center of the cradle. The cams rotate on a pin that goes through the bottom of the cam. The tolerance for the hole that the pins go through is very small, perhaps 1/2 inch.



I had an issue with the cams breaking where the pin goes through them. Trick davit covered a set for me as part of their warranty, but that set broke too. I solved the problem by taking the cams to a machine shop and having them replicated in aluminum. I have not had an issue since then. The mod cost a couple of hundred dollars but was well worth it.


I have a block and tackle that is tied around the stanchion base of the aft FB deck and leads down to the transom. I leave it attached all the time and use it to pull the stern of the tender up onto the cradle. It is possible without it, but much easier with it. The bow, being lighter, doesn't really need one, but I may install one anyway as my wife pulls that side and it would make it easier.



On a side note, I've found that block system to be useful for other things on the boat as well. I'd use it to help get an injured person out of the water onto the swim platform if I needed to.


Hope that helps. Let me know if you have questions.

 

[rantkiewicz]

Dingy Motor

I had a 9.9 Mer. that was to small. I went to a 15hp and it was the right size for 2 people to plane. I know have a 20 hp and it is perfect. The 15 hp4 motor is what I would get.

 

[smith6]

I have that exact dinghy. I have an 8hp on it. This AB dinghy seems to be a bit squirmy compared to other dinghy's I have owned. Although I would like to go faster I would not feel comfortable doing so in this Dinghy. Stick with the 9/9efi.

 

[Capt Dan]

We’ve always stayed small and slow for dinghy. I don’t want to get farther away than I can row back. And practice rowing your deflatable, wink wink.

We’ve done the Bahamas and go to the remote areas to avoid crowds. Read: “help is often a long ways off”. This next time we will have our Torqeedo on the stern of our Fatty Knees. So it takes us a couple minutes to get there, no sweat.

Bonus of a small outboard and small dinghy is no one wants to steal it.

You would be well advised to use that crane every single night without exception. You are designing a target. Just take good precaution.

Dan